I cut the lawn by push mower, and I prefer to use the older models that you have to work at getting them moving;l you clench your whole body cause those things are heavy. I use the self propelled one and set it on the fastest setting so I basically run behind it.
When ever I am sitting down for more than twenty minutes at a time (because sometimes I forget to get up and stretch my back) so I sit on an exercise ball. That keeps your muscles working lots, works my back and my core muscles strengthening them. Which is what I am after. So if I sit down and write parts of a story, I might loose track of more than half a day. At least sitting on the ball, I feel as if I have been more productive than normal.
My biggest change of lifestyle, has been working on my posture. I've had a lot of back issues this past year and I never want them again. So I have to work on getting rid of the midsection. Which means pulling my belly in tight, and REMEMBERING it when I bend, or weed my gardens.