Testosterone has nothing to do with fitness. It has to do with vanity. Taking it when you don't need it is never for fitness. Will it make you get bigger muscles? Probably. Does that have anything to do with fitness? No. Unless you're a professional athlete who has lost it and needs to cheat to keep your living or you're a bodybuilder, in which case looks are everything, I'd just avoid it and enjoy working out so you also avoid the health risks. Legality isn't the thing, it's that unless you're low in it you don't need it and too much isn't good for you. But if you're going to do this, you need to consult the bodybuilding magazines. Arnold Swarzenegger used to own most of them and they all told you how to do this kind of thing, so I'm sure they still do.