Great article and the section here about pushups grabbed my attention. We live in a fake world and fake pushups are no different - Youtube is full of them in their 1000s. 50 proper pushups is a serious achievement.
I set your same goal for my 70th, and got there - I had a PT stand by me and count minus one for every one not full range range of motion or otherwise fake. I did the 70. Since COVID mine have also fallen apart. I can barely do 30 now.
I've turned to running, despite hating it, and run 5km every day. That's been a learning experience, and I'd glad I took it up. Lot's of new Covid runners to nod to on the trail (running with a mask!).
Well done, keep it up!