For tennis ace-turned-"Biggest-Loser"-trainer Anna Kournikova, being green is all about growing and eating organic food and not wasting energy. "My grandma lives with me during the winter months and she actually grows vegetables in the back yard so I do get a chance to eat home grown vegetables most of the year. I try to buy organic fruits and vegetables whenever I can. Unfortunately, with all of the traveling I do, it can sometimes be a challenge," she says. While she's not a vegetarian, "I do recommend every food in its purest form. I try to eat lots of fresh fruits and vegetables and I try to do as much as I can at home to reduce my carbon footprint," she adds. "I do little things like always unplugging my chargers and turning off the TVs when they aren't being used at the time. I also make sure to turn off all of the lights when they are not in use, and I also let my laundry air dry rather than putting it in the dryer."

Kournikova, a longtime fan of "The Biggest Loser," pursued her new gig with determination, expressing her passion for fitness in meetings with producers. "They invited me to do a guest appearance on Season 10. I led the contestants through a tennis workout, and it went really well. I knew that day that this was the perfect fit for me. At that point we started talking more seriously and I was fortunate that there was an opening for me to work with the contestants on a consistent basis and I jumped at it. This is beyond my dream job," she says, calling the weight loss show "very inspiring. I love how its message is about changing people's lives and helping them lead a healthy lifestyle. At the end of the day, it's not about me or what I hope to achieve, it's about the contestants. I'm here to help them achieve their goals of losing weight, eating right and maintaining that healthy lifestyle beyond the show."

For Kournikova, the most challenging element has been the non-training aspects of shooting the episodes. "Even though this is truly reality TV, you still have to stop at certain times to do interviews and talk about specific moments. It can be a little distracting when you really just want to be in the gym with your team and burn calories," she explains.

The Russian-born Miami resident hasn't given tennis up totally, and still plays two or three times a week, "a bit more if I have a tennis event or exhibition coming up. I still love getting out on the court. It's been such a huge part of my life, and I love getting the contestants out on the court, too!" she says. Not surprisingly, her favorite workout is "anything that involves getting out of the gym. I love any physical activity like tennis, soccer or water sports," she notes. "I always recommend to people that they should try to do something that they love to do, and then it won't feel like a workout!"

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"The X Factor" stars are green and glam >