Be your own friend. I know, it is easier to say than done. But the basic idea is that we usually are harsher with ourself than with friends.
I mean, you look at your friend and think she is pretty, you look at yourself and think you are not. But it is not true. If you were a stranger to yourself, you would say "she is pretty".
And when I say "pretty" I also mean kind, intelligent, witty, funny... The key is to start looking in ourselves all those things that we would value in a friend.
And if you can do that on your own, your family and friends should help. Surround yourself with a "team me", people who remind you of all the good things you have. After hearing it several times, you would start to see it to.
Start small, if you tell your friend she is great at her job and you have been at yours for years, how can't you say the same to yourself? Same for everything.