Cameron Diaz’s life is up in the air.

Literally.

She has logged thousands of miles on planes, and that’s just in one recent week, with a whirlwind trip through New York, Miami and Vegas.

“I think I was meant to live on the road,” Diaz says, stretching out those magnificently toned legs that seem to go on forever. “I have been doing it since I was 16, and when I am somewhere for too long, I always get an itch to go someplace else.”

This pit stop in Los Angeles is just for the USA WEEKEND photo shoot and interview. A fizz of anticipation is in her familiar voice as she talks; she’ll be hopping on a red-eye flight right after the interview to Manhattan, where photographers will catch her the next day coming out of a gym with her boyfriend, Yankees star Alex Rodriguez.

At 38, when women in and outside Hollywood are feeling nostalgic about their younger, buoyant selves, Cameron Diaz has never lost hers.

“When you feel physically strong, it makes you feel different in the world and in your clothes,” Diaz says.

Ironically, the peripatetic actress has never been more grounded. She is in love and at the top of her game in her career, and with Bad Teacher, which lands in theaters this weekend, the superstar has never looked better or been a bigger box-office draw.

In her new comedy, Diaz plays a drunken, pot-smoking, foul-mouthed teacher from hell. Worse, she motivates her students to win a state competition so she can get breast implants to win over a wealthy substitute teacher played by her real-life ex-boyfriend, Justin Timberlake.

“We have always liked each other,” she says (they split in 2007). “I am not the same person I was when I was with Justin. Our lives have moved in different directions, and that’s OK.”

At 5-foot-9 and size 0, the ageless A-lister is whippet-thin, wearing jeans and a white shirt. Her face is bare of makeup, which is the way she likes it: “My skin is happier when I do less.” (At night she uses a light wash and moisturizer and leaves it at that.)

Still, even Diaz has had to make some concessions to aging. Gone are the days when she could eat fried food every day.

“I used to eat fried food from morning to night when I was in my 20s,” Diaz says as she sips a soy latte. “But I have really had to make some changes. I love fried chicken and french fries. I can’t do that anymore. As I get older, I realized I was working a little bit harder at digesting what I was eating, and I thought it is not fair to my body to keep doing this. If you are giving it a bunch of crap all the time, it will break down quicker and deteriorate quicker, so I stopped.”

Instead, in the summer she loves to grill fresh vegetables with herbs and chicken, fish, steak and shrimp, all with a swipe of oil. She adds salt after she takes them off the barbecue. Her breakfast of champions is a combination of egg whites, sautéed tomatoes and steel-cut oatmeal, all mixed together. She doesn’t eat white pasta or white bread.

One summer ritual she refuses to give up: hot dogs, beer and ballgames. All of it reminds her of her father, Emilio Diaz, an oil company foreman who died in 2008 at age 58 when a flu turned into pneumonia. Cameron, the youngest of three children and raised in San Diego, spent her childhood attending Los Angeles Dodgers games with him. Her mother, Billie, is an import-export agent.

“There is nothing like a Dodger dog and beer,” Diaz gushes. “It is such pure joy to have a great hot dog at a sporting event.” She likes hers with the works, including a healthy dollop of mayo.

And despite her jet-setting life, Diaz makes it all work.

“I can sleep anywhere, anytime.”

© 2011 USA Weekend.