My SIS said last time she saw his show she felt he shouldn't really be doing it anymore on account of the 'frailty' but I suppose he can't stop.
Probably true, but if you enjoy doing something, and it gives other people pleasure, why stop? Stopping might be a shorter route to the grave than carrying on.
My grandfather was forcibly retired at 65, a very fit man. He went through a couple of years of bleak depression, and then discovered his back garden (which for the previous 40 years had been nothing more than a large stretch of grass with a few shrubs down one side and bean poles down the other. Over the next few years he turned the back and front gardens into things of wonder, and actually won two prizes for them. Then he took on an allotment and started growing all manner of weird and wonderful vegetables, which he sold at church to raise money for a local hospice. He died of a heart attack, a week after his 95th birthday, while digging up some potatoes. Had he not discovered this hobby, I really think he would have been dead before 70.
I wouldn't be surprised if Doddy went the same way, only on stage rather than lifting potatoes.