Over the past two years, I developed an affinity for distance running. I went from non-runner to twice-over half-marathoner during that period. For the better part of those two years, I ran three or four times a week every week. I was never going to win a race, or place in my gender or age categories, but I steadily got better. Over 18 months, I cut seven minutes off my 5K time.

More than that, running cleared my head and it made me feel good. When I really hit my stride, I felt like I was flying.

Two months ago, while preparing for my second half-marathon, I started experiencing some discomfort in my knees. It subsided a bit and the race went fine, but it came back while I was recovering. When I tried to run again about a week later, it got worse. I went to a sports clinic. An ultrasound and x-ray yielded no evidence of damage to bone or tissue. The diagnosis was therefore chondritis*, and I was advised not to run anymore lest I abuse my knees and possibly end up with arthritis.

I could do without that, so I'm dutifully heeding the advice.

I realize that I'm quite lucky and that there are a whole lot of worse things that could have happened to me. Having said that, suddenly finding out that you can no longer do a thing to which you devoted a lot of time, and that you enjoyed immensely, is a bit of a bummer.

The thing about running is that once you get the bug, there is always a next thing: a new distance to conquer, a new time to beat, a new event to try. After cutting my half-marathon time by six minutes, I was ready to try to come in under two hours. I was thinking about pushing up to 30K next year. I thought that someday, maybe, the big one might be in the cards. None of those things will happen now.

None of this is particularly devastating — one half-marathon seemed crazy two years ago, let alone two — but I've just gained a whole lot of free time back. What am I going to do with it? Restart my stamp collection? Take up piano lessons again? Develop an affinity for speed walking (the doctor said that was OK!)? All of these things? None of them? Something else entirely?

If I've learned anything from this, it's that you cannot plan things out in too much detail because things can change and plans can evaporate. And that life is short and things go wrong.

I've decided to spend this summer doing things I've been talking about doing for years but always assumed there was time for. I now realize it's possible that there isn't time. You would think this would have occurred to me years ago, when I wrestled with the fact that I'd consciously put off reconnecting with a former classmate on Facebook because "I can do that later." He was killed in a car accident shortly thereafter. I never forgave myself for putting it off. He never knew that I was thinking of him.

So this is it. I've committed to not putting things off any longer. I ran two half-marathons while I still could. That was a good start, but there's more to do. Best do it now.

* There is still quite a bit of discomfort even after a month of completely avoiding high-impact activity, and it worsens when the air pressure shifts. So the diagnosis would appear to be correct. (Or at least it did.)