Oh Chutz, I know how you feel. Our brains tell us, 'We've done this before, we can do this again' and our foolish bodies believe us. I used to go grocery shopping by myself, or take my mother, load up the wagons, load on the belt, pack the bags, then into the car, drop them at my mother's house or my own and put everything away. Seriously, I actually remember doing that just a few yrs ago.
Now, I go early Fri morning - they open at 7am, we're there. One of my children is my helper, read 'Doer'! I make up the list, we go in their car, they push the wagon, I tell them which item I want, they load the wagon, the belt, the bags, the car, then bring it all in. I sign the check and help to put the stuff away upstairs, they put things downstairs. At the end, I'm beat. It takes me an hr to gather the energy to make a cup of tea and have an apple. I need to regroup. I get so annoyed w/ myself, but so grateful that my children come w/ me and we have an 'outing'. I switch 'helpers' each wk. 
Two wk ends ago we had a massive project here involving several rooms. My DD got the smaller project, the 2 DS's got the larger project - really back breaking, and my DH and I got the gross and messy project. The children did theirs in one day, ours took 2 days.
Neither my DH or I have been well as of late, so we worked, took a break, worked, break. We hate having to do things this way. We are both ppl that just want to get it done - NOW! I have limited use of my right arm/shoulder, I pushed it to the max. Two wks later it is still killing me. We were very happy w/ the finished job, but it feels like a set back physically, for both of us.
For most of my adult life, I have felt like I was 21, these past dozen or so yrs, not so much. I just feel old. I don't like feeling like I can't do the things I want to do, things I've always done. I will probably continue to do these &*^% projects and feel lousy after, just not as often as I used to.
Hope you feel better very soon.
God bless. Alice.