I remember back when my first son was born and got old enough to tear around our yard.  I — in great cardiovascular shape from decades of extreme bicycling — felt BRITTLE running around the yard with him.  It was around that time I read an article in on a cycling website that doing only low-impact exercise (like cycling) would lead to bone loss and poor overall condition.

It was about the same time I was pushed by some coworkers into doing a charity run (they had beer afterwards).  I was shocked to feel great during and after the run.  I’d run some in earlier years and always hated it because of the pain.  Now it felt great.

I started throwing it in as cross-training in the winter.  Then I decided that if I was going to be a runner, I had to do a marathon.  I did a few shorter races then trained up and suffered through one.  And trained more and did another.  And since then I’ve done a number of half marathons and shorter races.

It’s still painful sometimes.  But so is bicycling.  But now I can chase both my boys around the yard without any trouble.

And here’s a more recent article confirming everything I’ve experienced.