Oh, and Helen, I forgot to say you can learn this from the net/books etc ... but it is very hard.

Often aerobics video tapes will be done in mirror image, but not tai chi - left and right are very important, so looking at/deciphering photos or video involve a bit of brain gym.

Also, it is good to have others there to help you with breathing and posture (though big windows give an ideal reflection if you are watching yourself).

I recommend joining a group and learning with a master... it is very individualistic - no talking through out really - just the instructions or encouragement from your leader/master... but very good to be part of the group while you are getting used to it.

Once you have mastered the form you are taught you can take it anywhere.

I do it in the park, in my garden, by the ocean, and people are so used to this kind of thing now I never get a funny look.

Good luck with it, hope you get a chance to try it and you enjoy it...