how do I ride dick?!?

I've been having sex with my SO (first and only) for almost three years and I can't ride dick to save my life! I'm constantly changing how I do it and it doesn't pleasure me much at all. I feel bad making him be on top all the time and want to enjoy it. I try to go up and down because I get the best reactions from it but I get exhausted so quickly and he ends up doing the work. Please help! How do I make riding dick good for both of us??