From PEOPLE Magazine Click to enlarge
Jessica Biel

Whether she's running up all 189 of the famous Santa Monica Stairs, hitting the gym for butt-targeting lunges led by her trainer Jason Walsh or doing some hard-core hiking (she climbed Mount Kilimanjaro in 2010), Biel, 30, is always serious about exercise. "She doesn't ever take much time off," says her former trainer Ramona Braganza. And the actress is just as conscientious about her diet, making sure it includes lots of vegan and macrobiotic food but no alcohol. "It's so boring, I know," she's said. "But doing those things really helps."

Kate Hudson

The actress's foolproof plan for staying in shape? She brings her trainer on vacation! "I was in Italy with her last week," says Nicole Stuart, who's worked with Hudson, 33, for 15 years. "She ran 30 minutes every day, then we did Pilates mat exercises." When Stuart isn't available, Hudson (who had her second child, son Bingham, last July) follows Stuart's iPhone app routines targeting arms, abs, butt and hips. When it comes to her diet, the star simply exercises willpower. "I love pasta and pizza, but you can't have it every day," says Hudson. "Moderation is everything."

Jennifer Lopez

Having a specific goal always helps motivate Jennifer Lopez to stay in shape. In 2008 she competed in a triathlon to get her body back after having twins Emme and Max. Now she's staying fit for a 24-city summer concert tour-not to mention boyfriend Casper Smart, 25. The 42-year-old is working with trainer Tracy Anderson, who designed a custom routine targeting the area from Lopez's abs to her hips. "But we don't want her natural beauty to go out of balance," says Anderson. "[Overly] ripped abs would ruin her look." The game plan is obviously working for Lopez, who also does arm and leg work (using light weights) at least four times a week. "She loves the results," says Anderson.

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