Has anyone any experience of the American-style gym chain called Crossfit? There's one in London, I think. I'm somewhat intrigued by their, um, 'physical exercise philosophy', which is probably best described as evangelical. My personal fitness regime could certainly do with a kickstart, like so much else in my life but I don't know if I could cope, though, especially at my age, blah blah blah.
http://en.wikipedia.org/wiki/CrossFit