I took a ten week course of testosterone at a slightly higher dose than therapeutic (something like 175mg in a weekly IM injection). The most surprising aspect was psychological. I was 40 but I felt like a teenager again. Even at this dose, muscle mass noticeably increased. Fortunately didn't lose my hair or suffer any long term problems resuming normal T production. That risk increases with dose and duration on steroids. It only makes sense to use it at either low dose or short duration.