I am only a newbie as a trumpeter. After playing drums most of my life and getting used to a practice routine, practicing the trumpet is a whole new ball game. When I practice I start with a nice rich tone and I am now getting up to high C without to much difficulty. My problem is that after about half and hour all the notes above 3rd space C become a struggle and I get a lot of air going through the horn. I am so keen on practicing at the moment that I am going full bore and wearing myself out. Can anyone suggest how often I should rest while practicing or should I be looking more closely at my embouchure. I am using a King 7c mouthpiece and trying to keep my lips in the middle of the cup but I tend to bring my lips further to the top for the high notes. cheers.