I used to always worry about this before sexual experience. Once I became active in a relationship I realized how little this mattered in life outside of basic sexual desires. My partner experiences it much more than I do and I've been fortunate enough to not run into problems in this department. That said, there are so many ways to make your partner feel good there generally shouldn't be a problem achieving this (remember it is more about turn ons than just simple physical pleasure). Sex should be an experience both enjoy and you have to work at it some. If you make it all about you, it isn't going to be a good habit in the long run.