Oh and one more thing you will learn although painful.

Crashing hurts. Every ride I crash. I am always pushing myself and crash often. But by crashing often it becomes second nature and you become a better crasher. Your ability to climb obviously outweighs your other abilities/handling skills on a bike. Learn to crash and flow, and you will smoke most riders out there ...with your already kickass "up" endurance

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One other aspect that likely differs from roadies but mtbikers kind of stole from bmxers and skaters is the idea of sessioning. At least out here this is a very popular thing to do. Find a technical section on a trail and session it, ride the section (or walk) and turn around and do it again, until you get it. Its the best way to get good fast. Its also why some of us like lift assisted riding. I can hit a secion 20 times in 8 hours and really master it, where a xc guy (unless it is a small loop) would take 20 days to to the same thing. Sessioning really helps, it doesn't allow for a full ride for example, but it is fun and key to getting better.