I can't stress the importance of fundamentals too strongly. It's the thing which usually gets athletes out of slumps. Going back to fundamentals usually gives new insight from a new perspective to the things you "already know."
I went back to fundamentals this week-end. I, once again read Think and Grow Rich, by Napoleon Hill. It was the first self-improvement book I ever read when I was still a teenager. I've read it many more times over the years but, it had been several years since I'd taken the time to sit down and read it "cover to cover."
The ideas it prompted, reading it from my present perspective, were eye-opening, to say the least.