I used to be a bit of a 'jock', playing a lot of cricket and football (soccer), belting round the squash court and those sort of things. Even last year, I would think nothing of going for a 5 or 6 mile run (including with a hangover to collect a car left behind the night before). Today though, six months of inactivity hit me: at 2 miles I was struggling; I dragged myself to 3, but then had to resign.
"Kasparov showed to the world the importance of physical fitness to chess players. His training regimen included swimming, playing football and cycling. Truly, his high energy level kept him going." Hinduonnet
There are about 6 weeks until the tournament begins, I'm reckoning that's about 18 runs and a lot of sit-ups and press-ups. I can feel the lung capacity coming back already!
I once thought about Pilates as well and bought a book by Brooke Siler (she's famous for getting a number of Hollywood stars looking sleek), but so much is about correct technique and control that I think it would only really work with a good trainer alongside. So Brooke, if you fancy learning chess in exchange, give me a shout and I'm sure we'll be able to work something out.