Any advice on tackling a BIG cleaning job?

I was sick for 3 months (from an antibiotic resistent UTI), mostly bedridden, and my room is overwhelmingly messy now. Since I live in one rented room, that is my total home area. Also, due to my advanced age (75), if anyone gets a look at my room, I'd probably wind up being labelled with senile dementia and be put into an institution permanently. So I really need to clean it up here! But my age and recent illness have robbed me of both physical and mental energy. My get up and go has got up and went, as the saying goes. Yesterday I started my dreaded cleaning project and was exhausted after about 2 hours. Just sorting out clutter (plus 3 months worth of mail) and carrying bags of trash out really wore me out. I have come to realize I'm going to have to do this a little at a time.

Anyone been in this situation? How did you deal with it? Any suggestions?

Please don't suggest I get someone else to do it. I have NO family. I have little money. My friends live far away and are my own approximate age. This is a job I will have to do myself.