Coloring my hair used to be something I did totally for fun. Blond streaks, red highlights, dark brown -- my hair's been every color under the sun (including, once, an unfortunate shade of bright green after an ill-timed swim in the pool). These days, I rely on color less for fun and more for hiding those pesky grays that keep appearing. Do you remember when you spotted your first gray hair? (If you haven't spotted one yet, I don't want to know).   I turned 40 last year and honestly, I don't feel 40. Thanks to healthy eating and working out, my body looks and feels better now than it did at 30. But all the healthy habits in the world can't keep Mother Nature from knocking on the door. And it's not only aging that changes us -- just ask any woman who's ever given birth. The number on the scale might be the same and the clothing size might be the same...but the body? Not quite.   I had the opportunity to explore the topic of how a woman's body (and body image) changes over time in "Welcome to Your New (Old) Body," an article I wrote for VIV magazine. My experts made one message abundantly clear: If you want to be happy with your body as you get older, the most important body part to exercise is your brain. That's not to say we should all flop on the couch with a bag of cookies and call it a day -- healthy eating and exercise helps us look and feel fabulous, no matter what our age. But loving your changing body ultimately means appreciating all of the life choices and changes -- getting older (and, hopefully, wiser), finishing school, working, giving birth, surviving a loss or an illness -- that have brought you to the body you stand in today.   I'd be lying if I said I wasn't occasionally disturbed by the snap, crackle and pop that my bones make when I first get up in the morning. And though I'm in good physical shape, I have no doubt that a fit 25-year-old could easily outrun me in a foot race. And, yeah, sometimes I look in the mirror and wistfully remember my tiny pre-baby waist...but then I hear my son's belly laugh from the next room. Need I say more? In the end, I think accepting the body changes of aging gracefully is the most positive body image example I can set for my daughter.   How about you? What changes are you seeing in your body as time goes on? Are you accepting them, appreciating them or fighting them with all you've got?