I'm aware of the need for regeneration. Fortunately (?) I am not actually disciplined enough yet to do it every day; more like three days in a row and then a rest day. And other exercises in between sets to make use of that rest time. I'm not gonna aim for higher reps, but will eventually elevate my feet to make the push-ups harder.

Supporting the door to protect the hinges is an excellent suggestion, since concern about the hinges is exactly why I originally hesitated from using a door! It seems creativity is indeed the true limiting factor in choosing equipment and adapting exercises.

I think I will pick up running (many acquaintances are in a runner group), but dancing is also on my to-do list.

Many thanks for your kind suggestions!