The Trumpet Workshop

Hey, I was hoping people could comment on this with some advice:

I have been trying to develop my endurance and range on the horn but have been running into a road block. I'm not sure whether playing though exercises for a long time is actually helping or hurting my chops. I find that often my chops are sore and there is a big circle where the mouthpiece was sitting. Is it normal for the chops to be visibly marked after playing exercises, or should I hold off?