My daily playing schedule includes about 5 hours, and I get really tired at the end and can barely play anything, especially the high notes. What should I do to increase my endurance? Would the endurance excersises at the back of "A Physical Approach to Playing the Trumpet" work? Or shuld I just try to not play so much and so hard in the time that I have to play? Two of the hours that I play are self practice, everything else is sectionals and orchestra rehearsal.