The personal trainer, who turned 40 in February, appears nude in the July/August issue. Her toned body gives no indication of her age, although she admits "this birthday was hard."
"I thought 'Oh my God, I'm halfway through my life?" she recalls in the interview. "But when I think back on my 20s and 30s, I look better now than I ever have. Yes, I'm older, but I'm also wiser, and that's a more intrinsic type of beauty."
Michaels is best known for her role on NBC series The Biggest Loser. She trained contestants on the program for 12 of 15 seasons, and proclaims, "There are so many good reasons to exercise."
"It's important for women to have overall strength, because when you feel physically powerful, it transcends into every facet of your life," she relates. "The best thing about having strong arms is because I love to pick up my kids."
"What I finally realized is that you can't have it all," she concludes. "Do I want a better butt? Sure, but I'm healthy and can wear my skinny jeans, and that's good enough."