Before departing for bootcamp in 1995, I worked as a sous chef for almost two years. The trick to eating healthfully (I'm convinced) is built on a few principles:
1. Good, fresh ingredients. MB, if I remember correctly you're in Corpus now, so consider yourself lucky, because the quality and variety of produce options is outstanding. For dairy, I only drink organic*, fat-free milk on a regular basis, and while I enjoy real, full-calorie cheeses, etc, I only eat them sparingly. I also prefer organic free range* poultry/meats.
2. Preparation matters. I don't care how fresh and healthy an ingredient is, if you prepare it improperly, it will at best taste like crap. Worse, if you take something that otherwise would be very good for you and use an unhealthy cooking method (deep frying in saturated or trans-fats), you might as well just eat Whataburger or TV dinners all day, every day. In addition, certain cooking methods can actually destroy the nutrients in foods. An example would be boiling vegetables. Try steaming and poaching.
3. Watch your intake. By that, I mean pay attention to things like fat, sodium, sugar, fiber, alcohol, and overall calories. Too much sodium and fat lead to hypertension, heart disease, while too much sugar can eventually lead to diabetes. Not enough fiber in your diet prevents your body from flushing out detritous material from your intestines. Nasty? Maybe, but so is colon cancer. Much of this boils down to portion size, which is essentially simple math: If you stuff more than the recommended serving down your gullet, there will be an eventual, if not immediate, excess in your body.
4. From my perspective, two of the most important aspects are variety and to treat yourself every so often. Variety is pretty easy to understand, as people tend to like different sorts of things to eat. Personally, I cannot stand eating the same damn thing every day. I get bored. As far as the treating yourself goes... Well, there's just nothing wrong with having something you really like that may not be very good for you, provided you have it sparingly. It breaks up the monotony of things, and hey, chocolate is freaking tasty, not to mention very, very good for you in moderation.
5. This is more along the lines of eating cheaply. Use everything. I like roasted chicken, and I make it every so often. Most people toss out the carcass, but not me. I stuff it in a ziplock, throw it in the fridge, and when I've got a few hours, I make chicken stock, which is one of the single greatest things on the face of the earth. All the home cold remedies aside (and they actually are true), a good homemade stock is useful for many things. You can use it to make your own soup. You can use it instead of dairy in mashed potatoes. You can use it as a poaching liquid. And since you made it yourself, you control how much sodium and other ingredients go into it. Just skim the fat off of the top before you use it.
*--I know organic/free range products are more expensive, but consider a few things: Free range meats are way more flavorfull than the water-injected, mass-produced crap that gets passed off as meat most places. Organic dairy comes from cows that have not been treated with preventative antibiotics or RBGH, and (whether in addition to or because of that) it stays fresher, longer in your refridgerator, thus reducing the amount of wasted milk. Plus, it tastes better.
Here's what I ate on Friday:
-Breakfast: plain oatmeal w/ fresh strawberries, black coffee, apple
-Snack (3hrs later): one piece of low-fat string cheese
-Lunch: turkey sandwich w/ lettuce, tomato, spicy mustard; 1 serving low-
sodium pretzels; apple; diet coke
-Snack (3hrs later): 1 serving of low-sugar, dark chocolate (hey, it's Friday)
-Dinner: Poached halibut filets; steamed vegetables and potatoes; 1 whole
wheat roll; 2 glasses of wine; 1 cup thawed berries w/ fat-free
whipped cream
-I also took a multi-vitamin, lifted for an hour in the morning, and ran for 45 mintues before dinner
Edit: If you haven't already, go talk to the nutritionist at the hospital, and they will give you great suggestions/menus/eating plans.