Every single day, I deal with picky eaters both big and small. I'm the mother of 7-year-old triplets, all of whom have very different eating habits; I'm also a dietitian who teaches the professional athletes on the Chicago Bears and Chicago Bulls teams how to improve their diets. Although it's tough to convince a towering basketball player or a 300-pound linebacker that junk food is bad for him, trying to get my kids to eat well can be even more of a challenge. My daughter Kathleen has severe and life-threatening allergies to eggs, peanuts, and tree nuts, and Julia will not eat fresh fruit; luckily, my son, Marty, will try just about anything. Mothers constantly tell me that they feel guilty about their children's diets; they know how important it is to feed their kids healthy foods, but they're just not sure how to do it. Despite my own background in nutrition, I had to go through some trial and error with my triplets. Here are the most important lessons I've learned, which should help you guide your kids to eat better.