Every year I help the Shriners out by volunteering to play in their Big Band for a car show. It raises money for the Shriners. The job lasts for about 5 hours total. I messed up and agreed to play a church gig the same night as this obligation. I will be leaving the car show to drive straight to the next town for a rehearsal, dinner, and performance at the church. The church event is a paid gig. I get called several times a year by this choir director for performances at his church as well as other venues. I want to do the car show job and still have enough in the tank for the performance at the church. I know that endurance is built over time and there is no magic potion to build it in a short period of time. My individual and ensemble practice is pretty regular so I have a foundation to stand on. My question is how do some of you seasoned veterans prepare for a heavy day of performing? This day will mean at least 5-6 hours of face time. The gigs are in two weeks. I am thinking of putting in a lot of EXTRA time this week for practice and tapering off significantly in the week before the car show and church gig. I REALLY don't want to say no to either and sever connections that have been made. I also don't want to perform badly and not get called again.