@aaron @druid I think I'm familiar with the feeling, but I only ever went to the gym in school, and once to one of these modern things in the 80s.
But I imagine when you've cut split and stacked over a tonne of firewood in a day and bitterly regret it is similar..
My mate is a few years older than me and he's given up with the wood burners and has re commissioned his oil central heating. He hates burning fossil fuels but his body says he can't do it anymore. Mine isn't keen either.