Do you really have a need to serve?

I read a fair number of blogs, and as you can guess, most of them are written by subs. In many cases these subs talk about how much pleasure they get from serving their masters or how strong their need to serve is. I must say I find this difficult to believe. I have had only four subs for any length of time and none of them had a need to serve. Perhaps I don't inspire servitude in my subs, but I don't believe that to be the case. I feel a sub does her master's bidding because in pleasing him, the hope is that he will return the favour.
That doesn't mean that he has to do nice things, merely to do those things that drew the sub into the relationship in the first place. With my current sub things are no different. Just like in a vanilla relationship, if I satisfy her needs, she in turn wants to do the same for me. If either falls down on their end, the relationship suffers What makes a BDSM relationship different, in my opinion, is that a master can train or manipulate his sub to satisfy his own needs. If I need to feel like a dom or be sexually satisfied, then I can act or have my sub act to fill those needs. I can tell you that it is intoxicating to be able to have all your needs met. Unfortunately, there are times where in looking after my on needs, I have neglected my sub's needs. Lately our relationship has flourished because I have adjusted my requests or the manor in which I play with my sub to ensure her needs are met. They weren't major changes but enough to ensure both of us gain the most from being together.

Do you really need to serve, or are you serving as a means to an end?