funny thing... Nishio sensei was sometimes quoted for saying that high falls where not necessary after turning 40, but since I turned 40 I am finally beginning to enjoy those otherwise dreaded heavy impact clashes into the mat surface... I might still use my age to opt out of too many of them, but it IS getting easier for me to relax while being thrown, and as long as possible I will go on and allow myself to fly across the mats whenever possible.
Another thing: last weekend I attended a seminar with Ken Morinaga sensei. He teaches aikido and tai chi, and obviously have done a fair bit of yoga as well. He spend the better part of an hour on warm up and stretching for each training session, and I found myself in contact with muscles and tendrons that I didn't knew existed.
If I have a fraction of his flexibility and agility - not to mention timing and centered technique - when I reach the age he has now, then I would consider myself fortunate. Age is not preventing us from practicing or pushing our bodies. we just have to learn to push in a more gentle yet just as powerfull manner