Supermodel Adriana Lima starts preparing for the annual Victoria's Secret fashion show six weeks in advance. She works out for two hours a day, six days a week. Lima says she prefers boxing, jumping rope and isometric exercises that don't require equipment. "I don't lift weights, I don't like machines. Everything I do is with my body weight," she said. Lima keeps a positive attitude about working out.

"Every day's a challenge, every day you're stepping out and learning something new. So it's wonderful, I like it a lot. It's very intense, but I like it." She feels that working out helps her body cleanse itself of toxins.

Lima also shifts her diet, cutting back on carbs and upping the protein for three weeks before the runway show.

"I'm doing a combination of different protein shakes - it's called Metagenics," said the model. "Also, I only can eat green vegetables, everything grilled or steamed, or four ounces of any type of protein. And usually that's what I have for lunch and dinner, and every three hours in between I have a protein shake or cereal bar."