Septuagenarian Marathoner Gives Me Pause About My Own Plans

Back around 2010 I became a big fan of ultra-marathon runner Dean Karnazes, whose book Ultramarathon Man greatly inspired me to have a serious go at long distance running and accompanying races.  Just the other day while on YouTube I came across the name of Gene Dykes, about 73 now, who has defied all the traditional wisdom about how old age makes people more feeble and less athletic. After astonishing the running world with a marathon under three hours as a 70-year-old, he has, like Karnazes, gone on to tackle ultra-long runs, one of them a 250-mile event!  To these two I say bravo, but as far as I personally am concerned, were I to follow (more slowly, I'm sure) in their footsteps, my life experience of sometimes getting carried away with my success in an area would wear thin with me.  There are lots of cool areas in life to focus on, not just running: just looking at athletics, I see a more viable future for myself in swimming and, especially, speed-walking. But still, beyond sports, there are many things I'm interested in and I'd rather be immersed in them on a mediocre level than just continue going on to extremes in one tried-and-tested activity...but that's just me.  Still, there are a few remaining goals in running I'd like to get past first, and if possible, I'd like to continue the sport as long as possible as the years advance...