For me, the toughest thing to remember is photography is not a sprint--it's about taking the time to set up, compose, and execute a shot. It's about the thought processes needed to produce quality work, and employing what I've learned from others such as those of you who've taken the time to help me. As a shooter of baseball primarily, speed is probably the most important aspect, as you need to be quick sometimes, and don't have a lot of time to set up a shot. But since I've started shooting nature, landscapes, architecture, etc., I've had to learn a whole new set of criteria. Exposure, composition, and statement are all very important aspects of course, but my major hurdle is learning to slow down.
How about everyone else?