It's pretty simple, actually. I only eat when I'm hungry, only continue eating until full, and I only eat food I like. That's all.
That being said, I don't go completely crazy. I try to maintain a semi-healthy diet, limiting my sugar intake and eating vegetables and protein on a regular basis. But in my mind, life is too short to be worried about eating a doughnut. Yeah, you shouldn't eat the whole dozen, but I don't have time to mentally berate myself for the indulgence. It tastes good, and I'm allowed to enjoy my food. It just comes down to moderation.
Additionally, I don't strictly adhere to any "food rules", such as a number of carbs I'm limited to each day. I'm more concerned with eating food that will keep me fuller, longer. As a college student, meal times aren't a regular thing, and often they are very spaced out. I know that eating bagels doesn't keep me as full as peanut butter will, so I keep that in mind when I make breakfast. Chicken salad keeps me fuller than chips. Salad makes me feel better than French fries.
Am I trying to tell you that I am the pinnacle of healthy eating? Ha. Not at all. But I like to think that I'm doing a decent job. I don't have an achievement-oriented relationship with food, so I don't worry too much. Food is not the type of thing that should ever center around achievement. It's not an option, it's a necessity. That's why I hate calorie counting. If you're hungry, eat!
As far as exercise goes, I try not to adhere to any strict guidelines with that, either. Personally, I am incredibly achievement-oriented, and this tends to result in obsessive behavior and feelings of failure whenever I define success in any area of my life. In the area of exercise, this often leads to me ending up either injured or sick. It also sucks the fun out of the activity.
When I exercise, about 80% of the reason really is the mental benefits. I am a person who is full of stress and in desperate need of an outlet. I do yoga because it's pretty much the only time my frenetic mind grinds to a stop and finds peace. I also love cycling, running, and swimming, which calm my anxiety in a completely different way. When I do cardio, I spend a lot of time screaming in my head ("SWIM FASTER, PUSH HARDER, JUST DO IT"). It gets my aggression out. Yeah, the physical benefits of working out are great. But the mental benefits are more important to me.
I love feeling strong and confident, and I also love food. So I work out, and I eat food I enjoy. And it keeps me happy. I don't obsess over either one. There's so much more to life.