In my late 70s I think my riding days are over simply because I've stopped enjoying it. It took a while to admit to myself I was no longer disappointed if a planned ride had to be cancelled. There hasn't been any particular event or some sudden flash of insight rather the realisation has crept up on me. I'm selling my CB500XA, which is too heavy for me anyway, but keeping my riding kit. I've been following various threads on smaller street bikes and scooters as a lighter bike will be essential if I decide to return to riding. You never know.