Ellen Hendricksen in her book on social anxiety called How to Be Yourself recommends asking yourself what you would be doing if you were feeling confident - and then doing it. She says not to wait until you feel confident to take action.
If you tend to get yourself mentally and emotionally tied in knots, pay less attention to what you are thinking and feeling, and more attention to what you are doing. Take positive, healthy action, regardless of your internal state.
I also realized that it's okay, even necessary, to give yourself breaks from trying so hard. If you have been striving to be brave and do hard things, it's okay to give yourself a cozy, restful, down time.
And then a line from a hymn came to me: "Not what I am, but what Thou art." You can focus less on your own personal efforts and more on resting in what Love is.