Performance Anxiety Tips?

I've been dating a guy for a few months now, and almost every time I've had sex with him, my mind immediately starts racing and I find it extremely difficult (sometimes impossible) to either get hard or get to the point of orgasm. It's not because I don't think he's sexy or anything, because I really do, but I find myself getting so anxious and mentally worked up about it that I can't even get turned on or enjoy what's happening in the moment. I keep assuring him that he's not doing anything wrong and that it's all in my head, but I feel so bad because I can tell that he gets a little upset when I can't get off (upset because he just wants me to feel good and have a good time).I know performance anxiety is very common, but I've yet to have someone give me a clear cut strategy on how to overcome it for good. Anyone else try something that got rid of theirs?