How perfect is perfect?
When I find myself in that negative self-spiral, I try to listen to what I'm saying to myself. I hear a lot of "right" and "wrong" and "should have."
There's a right way to pour coffee, there's a right way to get up in the morning, there's a right way to dress. In my head there's a "right" way to do everything, and it's never what I am doing. The crazy thing is, that there really is no "right" way to do things. It's just some idealized picture I have in my head and an excuse to beat myself up. Are you doing that with your picture of yourself being happy? If I were just more positive, I would be happy - therefore I must be wrong.
I try to remind myself that maybe the way I'm doing things right now, is "right" for me, right now. Why should I accept someone else's idea of "right? (it would be so much easier if I could get that person OUT of my HEAD)."
The other thing I do is watch out for "should have." That's just another way of saying to yourself that you did something wrong. I try to catch myself and replace it with "I could have." That implies that I chose to do it that way this time and can make a different choice next time. No heavy "right" or "wrong."
Finally, I think the most powerful thing to stay positive is "Let Go and Let God."