Eeh, I can't play worth a damn either... but I'm also my own worst critic. I heard something a few years back, a list of common mistakes guitar players make, and how to get rid of them. It is actually pretty damn close to the list of tips from our resident Thor... err, Les, posted earlier with the addition of 1 more thing... making goals.
Ever since I read the original list, the thing I took away from it the most was setting goal for myself. Every time I practice now I set some sort of goal, and the practice doesn't end until I reach it. My goals are generally a bunch of short term goals to get me to where I want to be in a long term goal. Creating goals for yourself can be just as rewarding as recording yourself and listening to it a few months later. Set a goal for yourself, write it down, throw it in your gig bag, or in a random page of a song book, and start working on it. Eventually you'll run across the paper, look at it, and realize you know how to do what you set for yourself. If you don't know how to do it yet, put it back and keep working toward that goal.