I did this as a teenager and need to get back to it. Think of positive things about yourself. Look into a mirror, look into your eyes. Speak those positive things.
For example: I love you, I am intelligent, I am beautiful, whatever you think or want to think speak it into truth. I don't think I'm beautiful but I say it because often I've been told by men that I am beautiful. I'd say things like I have beautiful eyes. I am fit and healthy. But self love is important. It builds confidence. I love you as you look into your eyes in the mirror. Highly recommended.