I've been saying the same thing in many contexts, including cycling, for at least 15 years. A few years ago, in my 50s, I re-roofed my house by myself. It was pretty straightforward, just climb up there and nail down shingles, but people kept coming by making the usual comments about age, not accepting the passage of time, risking my life, blah blah blah: "Why are you doing that at your age?"
Because I still can, but won't always be able to. Because I'm a desk worker and enjoy the change. Because I saved between $5000 and $7000 with three or four days of work.
I'll be 65 in January, and every time I get on the bike these days, I remind myself to enjoy the ride, because I don't know how many I have left.