Hypnosis is indeed mind-altering. Through hypnosis, you can relax your mind and gain access to the 90% of your mind that most people are not even aware exists - I am talking of course about the subconscious mind. This is the part of your mind that controls breathing, heart-rate, and numerous other amazing functions. It also controls your habits, like smoking for instance.
If you drive, you might have noticed that when you started to learn first, you were pretty useless at it, and gradually with more practice you became so good that now you hardly even think about driving - you just do it. That's because you've practiced enough for the subconscious mind to take over that activity.
Now imagine if you could put that power to work for you in other areas of your life.....the possibilities are endless.