well, i certainly wish i had stuck with boosting my metabolism when i was young; i doubt it would have ever come back to bite me as hard as yo-yo dieting has. but i was also not sedentary then, and i definitely didn’t eat just boxed foods. i am eating more like i ate back then now, only healthier (we used to cook the life out of green vegetables, which i don’t do anymore).
i don’t count calories. but i am a geek. and after a lifetime of too damn much dieting, and wanting to shift my way of eating away from highly processed things, i needed a handle on what exactly i was eating beyond macro nutrients — whether i was getting all required minerals and vitamins from my food. so i tracked that for most of a year while i built my new recipe repertoire. it wasn’t all that annoying — i didn’t use a spreadsheet but a software program that contained the USDA food database, and which let me add my own foods and recipes, and then would spit out nice reports with graphs. i did the data entry during or right after i made the meal, so i wouldn’t forget. it became a habit pretty quickly. i can see how this might be very destructive for people with certain types of eating disorders, but for me it was freeing because i had already decided that i was never going to go on another diet, and i wasn’t going to undercut myself by counting calories either.
that was very instructive. i don’t need it anymore now, but it helped me gauge what sorts of things i needed to be eating, and in what amounts. and yeah, to be sure — lots of leafy green vegetables (slightly cooked, just to take the raw edge off) is the big ticket for me. i don’t even bother with a multi-vitamin anymore. i also eat several types of grains, and different starches.
habit-wise i am kinda between @David and “a wide variety of foods” — i definitely believe that the latter is the way to go. but i am busy, not a very inspired cook, and i don’t mind eating the same things over and over again, so i have built a number of meals that i rotate (i cook in large batches and freeze, and then only add fresh veggies at mealtime). fortunately for the “wide variety is good” idea i am always curious about new foods, especially fruits and veggies, and can add those easily — they go in a salad, or in the “curried tofu with random vegetables” meal, and if i like something i’ll find a good recipe featuring that item and it goes in the rotation.
from everything i’ve seen watching people doing serious lifting, deadlifts and squats are all you need to build useful abs. to actually look like the guys on fitness magazine covers, you have to have the right genetics, a diet that keeps your bodyfat very low, work out as your primary job, and good lighting. fitness magazines have a lot to answer for.