I have no problem with sexual stamina. I can last as long as I want. But I have problems with "body stamina". I get tired easily and have to change positions quickly. I want to be able to take a girl doggy for 15mins as hard as I can instead of 3mins and getting tired. What's a good exercise for that? I already do a full body workout 3 times a week (Squats, Deadlifts, Military Press, Chin Ups, Bench Press, Rows, Curls).