My first advice would be to lose some weight; at 180 you're probably as heavy as a 6'6" small forward. You can probably run 2-3 miles every morning to beef up your stamina, which might indirectly allow you to drill and scrimmage at peak energy for a longer amount of time. I don't know how increase your agility; that seems like something you would have wanted to start working on around 12 or 13 while you were still growing. Tennis, soccer, yoga and some kind of aerobics might help.
