Back in the early 1980s a young American, Alberto Salazar, was running some very fast times and people predicted he would win the 1984 Olympic Marathon in Los Angeles at the age of 26. However, one of the best coaches at the time, and really the guy that wrote the book on long distance training, Arthur Lydiard was asked to make a prediction about who would win, and he picked Carlos Lopez, who was 36 at the time.
The reason being that all other things being equal, in a marathon the person with the biggest aerobic base has the ability to run away from everyone else at the end. So when Meb Keflezighi at age 36 ran away from Ryan Hall at age 29 to win by 22 seconds over the final miles it should not be a big surprise. He may not be the fastest, but in a championship style race the race is typically won in the final miles and again, other things being equal, the person with the largest aerobic base will win.
It is also interesting to mention that Meb set a personal record at New York City in November at 2:09:13 on a relatively tough course, and then set a PR about ten weeks later in Houston at 2:09:08. When I tell people that I have a long way to go in running, that is what I mean, setting personal records twice at age 36. Now I might move on to something else long before then, and perhaps have a family or something, but the fact is, it takes a long time to reach your potential in this sport. One season or one year is not enough.
I feel like it is a good metaphor for other careers and for life. When will I peak in my professional career, 50s? 60s? 70s? 80s? No way! Not my 80s! But I just asked the question, and like a seed the idea will grow. The question will arise, is it possible to be on top of your game in your 80s? What about socially, with a family? At what point will I be most effective as a family member? I don't know, but the point is, I have a lot to look forward to in the future.