I am 23 and have been working out seriously since I was 18. I am at a plateau and seem to be going nowhere. I have switched my workouts and intensified them but still no luck. My main goal is to not get much bigger but to tone up and get firmer. My diet is good in terms of protein and carb rotation. I do 45mins of cardio 6 days a week. What cycle can i take to tighten up but not add too much mass? Please help.