I recently resurrected an application I wrote for a college project a couple of years ago. As I'm going through this code, I found a number of areas that needed some improvement. Not major meltdowns or security holes, mind you, but there were several places where I had unnecessarily written duplicate code, inconsistent naming standards, outdated comments, and at least one failure to explicitly close a database connection. In one case, I was actually creating a connection in three different functions to call the same stored procedure (from the codebehind page, not even in a data provider class!). A quick trip through the database structure found several tables that needed additional indexes for performance.
Though it was hard for me to believe that I could make such obvious mistakes, I actually looked at this discovery as a positive. This code proved to me how much I have learned in just two short years. Even though the application works well as-is (and got me an A in the class :), its shortcomings are proof that practice makes perfect.
So, if you're looking for a quick pick-me-up, dig up some old code you wrote and critique it. Moving forward, make it a point to save samples of your code over the years, to go back and pick apart later. You'll be glad you did.