A common technique to induce a state of hypnosis is called progressive relaxation. By relaxing each bodypart sequentially a state of trance can be achieved. This is a somewhat lenghty procedure, but it works nonetheless. This is however not the induction of choice for most hypnotists, because it's very time consuming. The technique seems to make people believe that you have to be relaxed to enter into the hypnotic state, but this is not the case.

Relaxation causes trance, but is not a requirement to achieve trance. Stage hypnotists will often hypnotize the subject while they are standing up, because this is more entertaining than a lenghty progressive relaxation, which could make members of the audience fall asleep.

So if you have any trouble really relaxing, tell your hypnotist this before the induction, that way he can use techniques that are better suited for you. That you have difficulties relaxing is not the same as being unable to be hypnotized, unless you have a very strong belief that this is in fact the case. It is not about what is "true" but more about what you believe that matters!