Life is a marathon, not a sprint. When I was 20 years old and an undergrad, I basically ran not at all. I ran a little for rugby and occasionally just to stay in some semblance of shape but that was about it. This pattern continued until I was 30 years old, out of shape, working tons of hours, traveling for business and my wife and I were expecting our 2nd child. Basically until I was so busy I couldn't imagine fitting one more priority into the pattern. That's when I finally decided to make the personal decision to be a runner. Now, almost a decade later, I run 3,000 miles a year while being the sole breadwinner for a family of 6, shuttling my kids all over, wiping noses and asses, taking care of a 100 year old house, helping with homework, organizing community activities and working probably 50 hours a week on a slow week.
Somehow having no free time makes me treasure my running time all the more and makes me crave something that's just for me that I'm in control of. Running is my decompression chamber.
I sometimes wish I'd gotten semi-serious about running when I was 20 years old and tried to find my true potential. I wasn't totally without talent. I wonder what I could have done, if I could have been a real animal.
But most of the time I'm just glad I'm running now and that's good enough.