Most of the time its all mental. I believe everyone has they're own unique way of approaching the horn with a daily routine. Warm up is mental focus that prepares your mind to get set on what is coming up in a rehearsal or performance. You gotta have discipline with yourself to establish a nice and good routine and not to the extent where you over due it. Take it easy rest as much as you play. Establish your mind to make it happen and as long as it works go for it and dont let go.