That’s wonderful.
And I love how you are working around your limitations. I try to do that too but I’m not as smart as you are at doing moderation. I overdo it, then have pain, then have to try to do nothing for a while. Your way you get a lot more done and have a lot less consequences. Maybe I will learn :-)
Use your timer. I use the one on my phone. Work either 10 minutes. Rest 20. Adjust as you need or to increase work time Always keep rest time more than work time until you feel stronger.
Sometime I come inside to rest. On sunny days I may rest in a rocker in the sun on the porch.
On nice days I try to work outside for at least half the day.