What do you all think of the addition of "positive" therapies such as meditation, visualization, yoga, tai chi, etc?

I'm going to be doing a meditation (quiet time to write, pray and think) and very basic Tai Chi soon. I've always wanted to take Tai Chi, but the classes are way too expensive and when you have to juggle finances with the doctor, well, the doc wins out. A very nice instructor here in town who understood I couldn't afford much, recommended some very good Tai Chi dvds (I ordered one today).

My mother has always been a big proponent of positive thinking. Working stringently on her diet and keeping positive, she's had 13 years of Adult Onset Diabets Type II controlled enough that she does not have to take insulin shots.

So, what are your thoughts on these therapies NOT as alternatives, but part of your overall health regimen?