The defendant, Tracey T. Dunlop, appeals his convictions for the murder1 of Carolyn Hawkins, two counts of robbery, both as class B felonies,2 and two counts of criminal confinement, both as class B felonies,3 and his sentence of life imprisonment without parole. In this direct appeal, he claims: (1) erroneous instruction on the defense of voluntary intoxication; (2) erroneous instruction on life without parole; and (3) improper sentence.
Instruction on Voluntary Intoxication Defense
The defendant first contends that the trial court erroneously instructed the jury on the defense of voluntary intoxication. He argues that it invaded the province of the jury, mandated a conviction upon the finding of certain facts, and mandated a minimum degree of intoxication, in violation of Article I, Section 19 of the Indiana Constitution.4
The defendant challenges the following language from Final Instruction No. 34 regarding the defense of voluntary intoxication, given over his objection at trial:
Mere intoxication is not sufficient unless there is some mental incapacity resulting therefrom as will render a person incapable of thinking deliberately and medi[t]ating rationally. A defendant should not be relieved of responsibility if he could devise a plan, operate equipment, instruct behavior of others or carry out acts requiring physical skill.
Record at 208. Citing Curran v. State, 675 N.E.2d 341, 344 (Ind.Ct.App.1996), the defendant contends that this instruction impermissibly invaded the province of the jury, violating Article I, Section 19 by mandating a conviction upon the finding of certain facts and by requiring the jury to find specific facts in order to accept the voluntary intoxication defense.
The Curran court found that this same instruction invaded the province of the jury in violation of Article I, Section 19 of the Indiana Constitution because it “ ‘[bound] the minds and consciences of the jury to return a verdict of guilty upon finding certain facts,’ ” Curran, 675 N.E.2d at 344 (quoting Pritchard v. State, 248 Ind. 566, 575, 230 N.E.2d 416, 421 (1967)),5 and because it “improperly required a certain degree of intoxication be proven before the jury could accept the defense.” Id. Nevertheless, the Curran court held that the erroneous instruction was harmless because “the evidence is such that the jury could not have properly found that.Curran was so intoxicated that he was incapable of forming the requisite criminal intent.” 675 N.E.2d at 345. In White v. State, 675 N.E.2d 345 (Ind.Ct.App.1996), the Court of Appeals addressed the same issue and found a similar instruction likewise erroneous but not harmless in light of the evidence.
*595A contrary view was recently expressed in Cheshier v. State, which expressly disapproved of Curran. 690 N.E.2d 1226, 1228 n. 2 (Ind.Ct.App.1998). The Cheshier majority observed that we have repeatedly used the challenged language in our opinions. Id. at 1228 (citing Legue v. State, 688 N.E.2d 408, 410 (Ind. 1997); Miller v. State, 541 N.E.2d 260, 263 (Ind.1989); Terry v. State, 465 N.E.2d 1085, 1088 (Ind.1984)). See also Horan v. State, 682 N.E.2d 502, 509 (Ind.1997). As Judge Sullivan noted in his separate opinion concurring in result in Cheshier, however, in none of these cases did we approve of a jury instruction containing this language. 690 N.E.2d at 1229. Rather, we were evaluating whether the evidence supported the giving of an intoxication instruction or was sufficient for the resulting conviction. While articulating our appellate rationale for these issues, we did not intend to create a trial standard for application by juries. The mere fact that language appears in appellate opinions does not necessarily make it proper for jury instructions. See Spence v. State, 429 N.E.2d 214, 216 (Ind.1981); Meek v. State, 629 N.E.2d 932, 933 (Ind.Ct.App.1994). Cf. Myers v. State, 532 N.E.2d 1158, 1159 (Ind.1989). We hold that it was error to instruct the jury that the intoxication defense was unavailable if the defendant “could devise a plan, operate equipment, instruct behavior of others or carry out acts requiring physical skill.” Record at 208.
As noted in Curran, however, such an erroneous instruction will not require reversal on appeal if we find the error to be harmless in light of the trial evidence. 675 N.E.2d at 344. The evidence at trial included the defendant’s audio-taped statement given to police shortly after he was taken into custody. In the defendant’s statement, he detailed the place where he obtained the knife before he went to the victim’s home, the sequence of events surrounding the stabbing, the locations where he found each item of jewelry he took from the home, and where the police would find the items he did not sell for cocaine. Having obtained a knife from a jar under the microwave in his mother’s kitchen, he then took his mother’s bicycle and rode to the victim’s house. He knocked on her door, entered, and asked where her children were. Learning that the children were asleep, he began to stab the victim, but one of the children entered while he was stabbing the victim. The victim told her daughter to run out the back door and tried to get herself out the front door, but the defendant grabbed the child and threatened to kill her because he “knew [the victim] wouldn’t go out that door and sacrifice her daughter’s life like that [because ... she [was] probably thinking ... [I would] stab [her daughter] too.” Record at 568. The defendant then grabbed the daughter and demanded that she help him find money or other valuables. While they were looking for money, a younger child awoke, and the defendant tried to keep her from seeing her mother, but ran from the house when he was unable to keep the child out of the room. The defendant returned to his mother’s house by bicycle. He washed the knife and replaced it in the kitchen. Noticing that his shirt was bloody, he removed it and hid it behind a chair. Then he went into the bathroom and washed blood from his hands and the rings that he had taken.
From this evidence, we conclude that a reasonable jury could not have found that the defendant was so intoxicated that he was incapable of forming the requisite intent. The instruction error was harmless.
Instruction on Life Imprisonment Without Parole
The defendant contends that the trial court erred in permitting the jury not to make a recommendation as to whether the defendant should receive life imprisonment without parole. He argues that when the jury was unable to reach a recommendation, the court should have required the jury to recommend against life imprisonment without parole. Instead, the *596trial court discharged the jury without receiving any jury recommendation and proceeded to sentence the defendant to life imprisonment without parole.
The defendant cites Burris v. State, 465 N.E.2d 171 (Ind.1984), to support his argument that the jury does not have the option to decline to make a recommendation. In Burris, an instruction stated that if each juror found that the requisite circumstances necessary to support a recommendation for the death penalty were not present, the recommendation “may” be against the death penalty. Id. at 189. We held the instruction erroneous because, in the case of a unanimous vote against the death penalty, the jury has no option — it must report its recommendation against the death penalty. Id. However, Burris did not address the question of the jury’s inability to reach any kind of recommendation, as occurred here.
The defendant further argues that the jury was given conflicting instructions regarding whether it was required to recommend against life without parole in the event it could not reach a unanimous agreement. Sentencing Phase Preliminary Instruction No. 46 included the sentence: “If you do not reach this unanimous decision [that a proven aggravating factor outweighs any mitigating factors found], you must recommend against sentencing Tracey Dunlop to life imprisonment without parole.” Record at 223. In contrast, Sentencing Phase Final Instruction No. 55 stated in part: “In order to return a recommendation you must all agree.” Record at 235.
The applicable statute provides: “If a jury is unable to agree on a sentence recommendation after reasonable deliberations, the court shall discharge the jury and proceed as if the hearing had been to the court alone.” Ind.Code § 35 — 50—2—9(f) (1993). The statute does not require the jury to recommend against life imprisonment when it cannot reach an agreement on the recommendation. Although the quoted portion of Preliminary Instruction No. 46 was inconsistent with the statute, the error favored the defendant.
Any error on this issue was therefore harmless.
Sentencing
The defendant argues that the trial court erred in finding and weighing mitigating circumstances; that his sentence violates constitutional provisions prohibiting cruel and unusual punishment6 and requiring proportionality; and that his sentence is manifestly unreasonable.
The jury found the defendant guilty on all six counts charged, but, as to Count I, it returned a verdict of guilty of murder but mentally ill at the time of the offense. The evidence established that the defendant obtained a weapon, rode his bicycle to a former co-worker’s house in search of money to purchase cocaine, and placed his bicycle where it could not be seen from the street. He then went inside the house, stabbed Carolyn Hawkins twenty-seven times with a knife and threatened to harm her twelve-year-old daughter, -an action which he later admitted he knew would stop Carolyn from leaving. He also forced her daughter to search the house for valuables, which he took. He then returned to his house, hid his blood-covered shirt behind a chair, and washed the knife used in the attack. Mental health professionals testified that the defendant was mentally impaired at the time of the murder as a "result of drug addiction. Other evidence showed that the defendant was under the influence of drugs at the time he committed the crime, that he came from a very dysfunctional family, and that he had expressed remorse for the crime.
*597Acknowledging that the trial court properly found a valid aggravating circumstance (intentional killing committed during a robbery) and numerous mitigating circumstances, the defendant argues that the trial court failed to give sufficient weight to all the mitigators and any mitigating weight to the evidence that he could be rehabilitated and reformed. In its thoughtful sentencing decision, the trial court found and weighed as mitigating circumstances the jury’s verdict of guilty but mentally ill, the defendant’s dysfunctional family background, his decision not to flee the jurisdiction, and his confession and expressions of guilt and remorse.
The determination that a circumstance is mitigating is within the trial court’s discretion, and the court is not obligated to explain why it finds a circumstance not to be mitigating. Taylor v. State, 681 N.E.2d 1105, 1112 (Ind.1997); Widener v. State, 659 N.E.2d 529, 533 (Ind.1995). The trial court is not required to give the same weight to proffered mitigating circumstances as the defendant does. Thacker v. State, 709 N.E.2d 3, 10 (Ind.1999); Montgomery v. State, 694 N.E.2d 1137, 1142 (Ind.1998); Battles v. State, 688 N.E.2d 1230, 1236 (Ind.1997). The trial court’s determination of the proper weight to be given aggravating and mitigating circumstances and the appropriateness of the sentence as a whole is entitled to great deference and will be set aside only upon a showing of a manifest abuse of discretion. Thacker, 709 N.E.2d at 10; Willsey v. State, 698 N.E.2d 784, 796 (Ind.1998). The record of the sentencing proceeding does not demonstrate that the trial court abused its discretion in considering and weighing the mitigating evidence presented by the defendant. We find no error in the sentence imposed by the trial court.
The defendant argues that his sentence of life imprisonment without parole violates Article I, Section 16 of the Indiana Constitution, which declares in part: “Cruel and unusual punishments shall not be inflicted. All penalties shall be proportioned to the nature of the offense.”
The constitutional prohibition against cruel and unusual punishments proscribes atrocious or obsolete punishments and is aimed at the kind and form of the punishment, rather than the duration or amount. Ratliff v. Cohn, 693 N.E.2d 530, 542 (Ind.1998); Wise v. State, 272 Ind. 498, 502, 400 N.E.2d 114, 117-18 (1980). Punishment is cruel and unusual under Article I, Section 16 if it “ ‘makes no measurable contribution to acceptable goals of punishment, but rather constitutes only purposeless and needless imposition of pain and suffering.’ ” Ratliff, 693 N.E.2d at 542 (quoting Douglas v. State, 481 N.E.2d 107, 112 (Ind.1985)). The sentence of life imprisonment without parole does not constitute cruel and unusual punishment.
We will find a sentence not proportional “ ‘only when a criminal penalty is not graduated and proportioned to the nature of an offense.’ ” Conner v. State, 626 N.E.2d 803, 806 (Ind.1993) (quoting Hollars v. State, 259 Ind. 229, 236, 286 N.E.2d 166, 170 (1972)). Given the circumstances presented in this case, we decline to find the penalty of life imprisonment without parole to be disproportional to the nature of the offense committed.
The defendant also claims that his sentence is manifestly unreasonable. A reviewing court may review and revise a criminal sentence, but only when the sentence is “manifestly unreasonable in light of the nature of the offense and the character of the offender.” App. R. 17(B). To warrant modification of an otherwise proper trial court sentence, we must find it to be clearly, plainly, and obviously unreasonable. Thacker, 709 N.E.2d at 10; Brown v. State, 698 N.E.2d 779, 784 (Ind.1998); Prowell v. State, 687 N.E.2d 563, 568 (Ind. 1997). The sentence imposed in this case is not manifestly unreasonable.
*598Conclusion
The judgment of the trial court is affirmed.
SHEPARD, C.J., and BOEHM, J„ concur. SULLIVAN, J., concurs and dissents with separate opinion in which RUCKER, J., concurs.. Ind.Code § 35-42-1-1 (1993).
. Ind.Code § 35-42-5-1 (1993).
. Ind.Code § 35-42-3-3 (1993).
. Section 19 provides: "In all criminal cases whatever, the jury shall have the right to determine the law and the facts."
. Pritchard, is principally concerned with instruction language that is mandatory in nature, thereby taking from a jury its right to determine the facts and the law under Section 19. Pritchard, 248 Ind. at 575, 230 N.E.2d at 421. The voluntary intoxication instruction in the present case does not contain directive language equivalent to that in Pritchard, 248 Ind. at 568, 230 N.E.2d at 417 ("then you shall find such defendant guilty"). But see Parker v. State, 698 N.E.2d 737, 742 n. 9 (Ind. 1998).
. Although the defendant cites the Eighth Amendment of the U.S. Constitution, he provides no authority regarding any applicable principles and makes no separate argument. Such claim is thus forfeited. Ind. Appellate Rule 8.3(A)(7); Kindred v. State, 540 N.E.2d 1161, 1168 (Ind.1989).