Indeed, people like Ms. Leavitt often fail because they rely on the same strategies that have failed in the past, said Karin Schlanger, the director of the Brief Therapy Center at the Mental Research Institute in Palo Alto, Calif., which works with people trying to break destructive behaviors.

But while change may be difficult, Ms. Schlanger and other psychotherapists, addiction counselors and life coaches said, it is not impossible. Even Mr. Deutschman, who acknowledged the low success rates of most change regimens, said certain strategies were more likely to bring positive results. He boils his conclusions down to four steps.

The first, he said, is to "start with big changes, not small ones," a strategy likely to yield immediate, noticeable benefits that inspire more positive change.

The second is to act like the kind of person you are trying to become; even if you hit the jogging trail with 30 pounds of flab, think of yourself as the jock you want to be. The third strategy is to "reframe" the situation. Recovering alcoholics, for example, have a higher chance of success if they reframe their sober life as a divorce from a tumultuous love affair with drinking, because they can then look back at their old life as a romantic adventure, rather than a sinkhole of regret. The fourth, and crucial, strategy, he said, is based on the "don't do it alone" advice that is the bedrock of 12-step programs.

• Lose Weight
• Manage Debt
• Save Money
• Get a Better Job
• Get Fit
• Eat Right
• Get a Better Education
• Drink Less Alcohol
• Quit Smoking Now
• Reduce Stress Overall
• Reduce Stress at Work
• Take a Trip
• Volunteer to Help Others

Adele, 20, Singer, London

PROFESSIONAL: My main priority is the second record. I'm really looking forward to getting right back into the thick of recording again.

PERSONAL: Keep enjoying everything and avoid crumbling when stuff goes pear-shaped. Get a better balance between my career and personal life.

*****

Chris Brown, 19, Singer, Tappahannock, Va.

PROFESSIONAL: I plan to complete my new album, "Graffiti." I do my first European arena tour in January. Since I've also started songwriting, I plan to put together my writing team.

PERSONAL: I hope to achieve all aspects of success in a lot of different areas.

*****

Martha Stewart, 67, Magazine publisher, television personality, entrepreneur, New York City

PERSONAL: I rarely make New Year's resolutions because I believe in constant evolution and change. Resolutions and contracts are very similar -- they need constant tweaking and editing to work really effectively.

*****

Katy Perry, 24, Katy Perry, Singer, Los Angeles

PROFESSIONAL: I would like to sell out every date on "Hello Katy," my first world tour.

PERSONAL: Stop reading my own press.

*****

Mitt Romney, 61, Former governor of Massachusetts and 2008 Republican presidential candidate, Belmont, Mass.

PERSONAL: Stop wearing a suit and tie to bed.