Being submissive means submitting to the will of another. (Redundant, I know.) There are varying degrees, and it does not necessarily mean blind obedience. What it means for one person does not have to be what it means for another.
I find submitting pleasurable, even though I sometimes do not enjoy the acts themselves. I do have some limits in place, and will not do something I find morally objectionable. Beyond that, I take pleasure in pleasing others, above and beyond my own desires.