Holy crap some of you people do alot of drugs! A multivitamin should be more than enough. Cripes I'd like to add muscle mass, but I'm not going to shut down my kidneys, liver and heart so I can regain muscle mass. I work out almost everyday alternating weights and aerobic, and put on no muscle mass, but I can live with that over having transplant surgery in a few years and not working out at all.
From what I've seen of my kids the best thing to do is vary your workout routines. Cycle through different lifts when you are lifting over a week or two, and try to vary the aerobic end also, although I admit I find that harder to do. The treadmill is there, but having to run to the pool is a headache and too much time.
Eat right and you can get all the crap you ingest from phony health companies and doctors in the right and natural quantities.