Proving once and for all that old dogs CAN learn new tricks
Seriously though, people often find more incentive to make those changes as they age. For a start, you own mortality tends to become more salient and you start noticing the long term effects of (as you put it) "gross corpulence" (e.g. high blood pressure, heart disease, cerebrovascular changes, diabetes etc) that as a young or middle age person might seem so far away.
The other thing is that many of the obstacles start being less of a problem (retirement means you can focus more on yourself, less stress, more time to cook well, kids and the demands thereof might have left home etc)
But on the other hand, with age comes habit and they can be hard to change.
Either way though it's a good idea to make the change, no matter what age you are! Good on them!
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"