I'm with Wyl and Alex. Why would you? Masochism is sex, and sex is about enjoyment. If lot's of pain doesn't make you hot and horny, demand from your boyfriend/master that he doesn't cross the limit. A master who doesn't respect that limit is best avoided.
edit: Sure, you may want to put up with stuff that doesn't make you hot because putting up with it is a big part of the submissiveness thing for you. But you should acknowledge that. In a situation like that, enduring more pain, is counter productive.