I'm learning to be my own best friend. You'd think from reading my blog I have a healthy self image, but believe me, all my bragging is just over compensation to how I really feel about myself. So I've been purposely saying nice things to myself every time I feel down. (And if you heard the things I say to myself you'd wonder how I get my head through the door!)
I know this works because for one I've read it in so many books over the years. "You are what you think".
But also, I have an anecdote. I have a friend who used to have a severe social phobia, and could only get cleaning jobs. One day she started reading her bible out loud every morning and saying out loud "I AM A PRINCESS OF GOD". Well, that gave her the courage to start volunteering at Citizen's Advice bureau, and then that lead her to a job in a department store. I remember when I used to visit her for a cup of tea, I'd have to bring the tea bags, milk AND sugar. She'd barely have enough toilet paper and not all of the lights had light bulbs in them. Now she has all those things and more!