It's fine to do something with your partner just for their sake; but maybe you would feel more fulfilled if in return, he did something that you like. What is it that you are seeking from him in bed? Do you get that from him? If there is something that you like and enjoy, ask him if he can do that for you in return, even if it's something that seems simple and small. I've always felt that so long as both people feel whole and satisfied at the end, then it was good sex. And if you can't have them both at the same time, as Denu said, then take turns. Sometimes it's easier to do something 'for' someone when you know they'll do something for you the next time.

As far as enjoying it goes, I get it from seeing how much he enjoys it; mmmm I'll do anything if it makes that cock nice and hard and purple....*drools*