Absolutely. That applies to everything in life though. Everything from getting your drivers licence, to finishing school.
What I'm saying is that I don't think it should be classed as a 'fad', a la ab rocker et al.
The only bad thing I have to say about it is that Tony Horton (the 'Coach' that leads you through the series) gets annoying after a while. Once you know how to do the exercises, mute the TV, and crank the stereo. (It still has text to tell you what you should be doing anyway).



