Perfection-Free Zone

Often, what has really messed me up in the past is aiming for perfection when I've been trying to set fitness or healthy eating or stress management goals for myself. Then I end up getting really frustrated with myself and giving up. (I hate failing at anything, even programs I've devised for myself.) So I've learned over the years that while I need goals and structure, I also need to factor in flexibility and the inevitability of failure or else I'm doomed right from the get-go.

What have you learned from previous health improvement programs you've designed for yourself? What are the ingredients for success and/or failure for YOU?