Tracy Anderson, 38, empties her purse for Us. Credit: Michael Pirrocco

Tracy Anderson is keeps snacks and toys for 16-month-old Penelope in a Chanel tote, a present from client and business partner Gwyneth Paltrow. "She always gives 'wow' gifts," says the pro, who also works with Jennifer Lopez and Nicole Richie. What's she packing?

Bottoms Up!

"I worry about getting stuck somewhere without water for Penny or my 15-year-old son, Sam. It's a weird concern of mine. So I carry Alka-Pi water, even though my friends make fun of me for lugging heavy bottles everywhere."

Words to Live By

"I love Stefan Sagmeister's photo book Things I Have Learned in My Life So Far. He's a graphic designer who makes living-art displays that spell out phrases like WORRYING SOLVES NOTHING. The messages inspire me."

Smooth Operator

"Bioelements Vitalization Body Creme is my must-have. Perfect after a flight!"

Medicine Woman

"I bring Benadryl with me even though I've never taken it. I just fear I'll someday have an allergic reason!"

Priorities in Order

"I always have a chocolate bar. Basically, my essentials are chocolate and water, but what more do women need?"