While I'm going to try not to criticize your goals it's important to realize that to be healthy one needs a good diet and proper lifting if you're going this route. Gaining muscle will make you healthier. Deadlifts, squats, bench press, over head presses, and cleans will do you wonders. I reccomend a 5 reps X 5 sets to begin. You need to push yourself, do as much weight as you can for the amount of reps you're doing while having PERFECT FORM. So let's say you're doing a squat but you're only going partially down, instead of having your upper legs paralell to the floor or beyond parallel you need to perfect this form and maybe drop the weight a little bit. If you're deadlifting and you're rounding your back to get the weight up, you need to drop the weight 5-10 lbs maybe to get that form perfect. Bad form has potential to cause injuries, slow down your progress, etc.
Buy in large quantities, you can upkeep a very cheap diet, look in the right places buy the right things. I can make calorie and nutritionally dense home cooked meals for under $3 with 600-1000 calories.