50+ Fitness

So here's that very disturbing Snowbook :-) and what on earth does this man think he is doing? Swimming? In the open sea?
I have quite a few friends, in fact make that loads, who will adore this book and to whom I'm a complete disgrace, in return they are to me a constant source of guilt. There they are 50+ and suddenly taking up marathon running or competitive rowing (that's rowing as in Steve Redgrave, not rowing as in arguing) or training for The Three Peaks Challenge (this is not about beating egg whites for a meringue) or worse, and this is awful, The Ironwoman (and this is not about pressing your clothes).
I know I should be concerned about the nation's fitness, it's doubtless a government target that I've had many an e mail missive about and deleted.I feel I keep reasonably fit at work, a morning of two year old developmental assessments and you certainly work off your breakfast calories.However I must admit nothing counters the effects of gravity so this winter I've reluctantly signed up for a Pilates class.
By all accounts I will be a foot taller by Christmas when I have located and recruited all those forgotten muscles, meanwhile my transverse abdominus would seem to have gone on a very long and lazy holiday and hasn't been seen since."Navel to spine, feel that muscle working", er, well no, not excessively.
Forget cross channel swimming, how can lying on a mat on the floor, breathing in and out and occasionally raising an arm and a leg be so exhausting? After an hour of this strenous lying down I had to go home and award myself a further hour of reclining with a good book.