[Hysho]

In my free time, I no longer have the energy for something useful

Same.

Inevitably, the older you get, the less energy you have to engage In physical activities.

I recently learned how to Embroider so I can make patches and some designs to sell or put on my shirts.
As of right now, It's going well and I just finished my first project that took me around 3 days!

Why don't you try out stuff like Embroidery? It's not that physical but it's really fun.