I didn't begin as a runner. In my 30's I ran a couple 10Ks. But it was always a goal of mine to run a marathon and in my 39th year I decided to do it before I turned 40.
And training and running for 9 marathons and 6 half marathons puts a lot of time on the road. During that time I keep learning, and relearning, and relearning lessons. This is why I keep running... because I need to keep reminding myself.