If you have access to a gym, I joined a gym 3 months ago and so far I'm up from 130 pounds (emaciated with virtually no muscle, result of opiate addiction for 10 years) to 158/159 and able to lift 2-3 times what I could in each muscle group before I started working out... I'm doing 20-30 minutes of cardio on the elliptical or exercise bike every day (I'm at the gym 5 days a week, 3 days on/1 day off) and I never get out of breath anymore really, except at the end of the my cardio since the point is to push yourself. I'm in better shape than I've ever been, and I feel great. It doesn't really take a lot, I go for an hour a day including stretching at the end, and I'm eating a lot of protein (and eating well in general) to build muscle faster. You could do it at home too but I find that much more difficult to do, mostly because there are distractions, and because I don't have any equipment or weights. The cardio is the most important part, that and getting your core muscles strong.