Getty ImagesSometimes celebrities don't live the-whether it's smoking, crash dieting, or just staying in unhealthy relationships.
Other times, they have to deal with serious health problems. Or they've assembled an A-list team of trainers and nutritionists to help keep them slim and trim.
Here's where 8 celeb power couples weigh in.
Justin Timberlake and Jessica Biel
The Grammy-winning singer and the 7th Heaven actress have been photographed running together near their apartment in New York City. Both are serious about strength-training, as is evident by their toned physiques.
Timberlake shaped up with a grueling bootcamp while filming Alpha Dog in 2006, and Biel gets her famously toned arms by doing push-ups. "Everybody I train ends up doing push-ups at some point because they are so beneficial. They help you get incredible arms!" says Biel's trainer, Jason Walsh.
Tip to steal: Work out with your partner. It's a great motivator and increases endorphins.
Health.com: Surprising celebrity BMIs
Ashton Kutcher and Demi Moore
Demi Moore has always kept herself in shape. Now, she and husband Ashton Kutcher share their admirable workout routines with their million-plus followers on Twitter.
But they're more than just a super-fit couple-they also do a good job of keeping their marriage stress-free. "We deal with issues before they become arguments," Kutcher told Parade magazine in 2006.
Tip to steal: Tweet your progress. Research shows that blogging or keeping a journal can help hold you accountable to your health goals and aid in weight loss.
Will Smith and Jada Pinkett
This fit power couple knows the secret to a healthy marriage. For his role in I, Robot, Smith shrunk his body fat to 7.5%. (The average American male has approximately 17% to 19%.)
Pinkett-Smith is a yoga advocate. "I usually do my yoga at home in the evenings for about an hour," she told Women's Health in 2005.
They spend quality time with their family but don't feel guilty when they are away. "I make sure I get jobs so that I can go away and have promotional tours and have an excuse to be alone," Pinkett-Smith told People. But the distance doesn't worry Smith. "I knew you were that person for me because you're loyal, to a fault," he said of Jada in Essence in 2008.
Tip to steal: Maintain your independence. These lovebirds have their own lives, but cherish their time together.
Health.com: The best and worst celebrity health tips
Josh Duhamel and Fergie
Singer Fergie (born Stacy Ann Ferguson) knows how to keep her-and husband Josh Duhamel's-"humps" in great shape. The couple is well-known for outside workouts, often running and doing push-ups. A former crystal meth addict, Fergie is now fitter than ever, and even lost 13 pounds in 2009. "Fergie is very disciplined," says trainer Natasha Kufa.
Fergie and Duhamel take time to themselves too. "He just dances for me in private," the singer told Playboy in 2007. They also enjoy quirky, romantic activities such as fishing, karaoke, and painting. "We stay out of the spotlight as much as we can." says Duhamel.
Tip to steal: Find new ways to bond. Long-term couples that try new experiences are happier.
Ozzy and Sharon Osbourne
Though this couple's marriage may be strong, their healthy ways are debatable. "Yes, well, it's been well-known that I'm an abuser of drugs and alcohol for the best part of my life," Ozzy admitted to CNN, but claimed to be attending meetings to stop drug use completely.
Sharon was diagnosed with colorectal cancer in 2002. She had her left descending colon removed and followed the surgery up with chemotherapy. But she's no stranger to surgery: "I made fun of the ladies who were nipped, tucked, and pulled. That is, until I joined the club. Now I've got my membership; I'm not going to let it expire," Osbourne told People.
Avoid this trap: Get regular checkups and screenings to prevent chronic disease.
Health.com: 10 medical tests women need this year
Sean Penn and Robin Wright
Both Penn and Wright have successful acting careers, but, in terms of health, this couple doesn't top the list. Penn met Wright while bumming a cigarette, and both continue to smoke. Penn even lit up two cigarettes during a 2008 news conference in Cannes, defying French smoking laws.
They began dating shortly after Penn's 1989 divorce from Madonna and were married in 1996. The couple announced divorce and separation plans in both 2007 and 2009, and finalized their split in 2010, which may have affected their health-and certainly their stress levels. Divorce and separation are associated with increased anxiety, depression, and risk of alcohol abuse, according to a 1997 study.
Avoid this trap: Avoid conflict by using these ways to cope with relationship stress.
Blake Fielder-Civil and Amy Winehouse
though this couple divorced in 2009, their health problems are still going strong. A smoker since she was a teenager, Winehouse has also been arrested for marijuana possession. The singer has kept up her cigarette habit and was admitted to the hospital in June 2008 for "scarring of the lungs, which could lead to emphysema."
Fielder-Civil was in jail for more than a year awaiting trial for assault and attempting to pervert the course of justice, and checked into rehab upon release. After seeing tabloid photos of Winehouse with former rugby player Josh Bowman, Fielder-Civil filed for divorce, and the couple has only been spotted together a handful of times since.
Avoid this trap: If you or your partner smokes, quit smoking together. A smoker is more likely to kick the habit if a spouse does.
Health.com: Crazy ways smokers finally kicked the habit
Bobby Brown and Whitney Houston
These singers are no longer together, but take a lesson from their dysfunctional relationship. Brown was arrested for a bar fight, driving under the influence, and violating parole. "I would spend like, I'm talking, days to weeks just high," Brown told Stone Philips in a Dateline interview. In a 2002 interview with Diane Sawyer, Houston admitted they had both used alcohol, marijuana, cocaine, and prescription pills. She has entered rehab twice for substance abuse.
"They fought like cats and dogs," a relative told People in 2006, and Brown was accused of assaulting Houston. After a bitter custody battle for their daughter, Bobbi Kris, the couple is now on better terms.
Avoid this trap: Drugs and alcohol put you at risk for domestic violence. Get tips on how to avoid abuse.