I have a few of them that I like.

If you can't fly then run,
if you can't run then walk,
if you can't walk then crawl,
but whatever you do
you have to keep moving forward.

Never regret a day in your life:
good days give happiness,
bad days give experience,
worst days give lessons,
and best days give memories.

Rule your mind or it will rule you ~ Buddha

You have not failed until you quit trying ~Gordon B. Hinckley

Look in the mirror. That is your only competition!