TODAY I PROMISE NOT TO SHOULD ALL OVER MYSELF!
"Should" is an easy trap to fall into. We can exert so much time and energy into fretting about our mistakes and failures. On a small, everyday mistake level, this just causes us to worry, waste time, and drive everyone around us a little crazy. On a larger, more eternal scale, God has put our past sins behind Him, so we should feel the freedom to put them behind us as well.
Don't live in the past. Learn from your mistakes, but move past them. I'm reminded of the lyrics of an old Steven Curtis Chapman song - "Remember your chains, but remember your chains are gone!"