> I had no idea I could run these longer distances, and was not even planning to run.

I know I can't run. Never could. My lungs just close up after even a short run and the rest of my body promptly follows.

I could walk though but despite walking few kilometers each day this summer best I could do was squeeze a minute or two of running into my walking.

And even walking ended when my feet arches began to hurt from overuse. Since then I stopped walking regularly and switched to 'barefoot' shoes and my left foot pretty much healed but the overuse injury in the right one pops back up when I walk for about an hour. I am not overweight and have high feet arches.