Sometimes when your trying to work yourself to your limit it isn't lack of sleep, diet at all. Obviosly that helps a hell of alot. I'm sure everyone will agree most of it is mental. I think I only really realised this about 5 months ago whilst pedaling uphill on my downhill bike. Got halfway up and started thinking, "I'm aching now, I'm going to push" but instead I pushed through that barrier and pushed into the burn which I had never really done before because my mind never let me. The best way I can put this into trials perspective is say your going for a big up, just size it up in your head and then swear alot in your mind, for example "I'm gonna nail this f***in* thing, come on you lump of s***" Just force yourself that little extra, theres always something lurking in you. Waiting to burst out, its all about harnessing it. Which I think, takes alot of work.