Treat yourself like you would treat someone you really love.
Something like that, it's part of Louise Hay's How To Love Yourself, a one-page list of things. Also I learnt from Effortless Mastery (about piano playing) to stop all the negative self-talk! Which I used to do a lot. Saying awful, cruel, mean, self-defeating things to myself that I'd never say to someone else. Being kind and patient with myself. I guess I had to learn that while it's great trying to being kind to everyone--you yourself are one of those people. That also helped overcome the very low self-esteem I'd been bullied into at school and at home. And helped with happiness in life. :-D