I try to take a page out of my grandmother's book on this one - I tend to try to make everything perfect and I fuss over every stitch and can work myself into a lather over every crooked seam and want to trash whole projects...then I remember my grandma - she would deliberately put at least one block in wrong into most of her quilts. Maybe a pinwheel that goes the other direction, or a block in the wrong shade. Not big glaring mistakes, just something sort of subtle but noticeable if you looked long enough. She said it kept her from worrying too much and kept the quilt more fun to work on. It kind of was her signature - her quilting friends would have fun trying to find the "mistake" in her finished quilts and they were always popular in shows. Personally I still have plenty of honest screw-ups in my quilts but some day when I reach her level of skill I just might copy her idea.