Here's an interesting article that sheds some light on the history of relaxation techniques:
I'm a firm believer in both camps:
- relaxing the body relaxes the mind
- training the mind (visualisation, mantra) leads to relaxation
They both lead to the same place, although you could have a hearty debate about the different mental factors present (if you knew anyone to debate such things with). Ah, it doesn't matter what you do as long as you do it. Go for the chilled out, super relaxed, happy, calm person who's hiding in your heart and enjoy it all.