I have a lot of great games in my backlog and sometimes is hard to choose one, because I would like to play them all. The monthly theme is actually very permissive and you can easily find 3-5 games that fit the theme, but besides that, it's easier for me to find a game that fits the theme and stick with it until I finish it. I am somehow more motivated having the 'external' help.
I have very less spare time, I have a baby girl and another kid on the way in a couple of months, so my only spare time is 1-2 hours at night (but not every night) after everybody fall asleep.
Regarding your illness, I'm really sorry to hear that, but I hope your curation is for the best and you can go through it as easier and comfortable as possible. Maybe gaming even helps you by distracting your attention and mind from other stuff and comforts you a bit. As we grow older it won't be any easier, but... I still enjoy saying: Never stop playing !