Admitting my limitations has become a big help, but it's a slow and painful process. I have a jumble of these stupid diseases impacting everything from my intestines to my joints and skin and even my inner ear.
The thing that was the hardest to let go of was mowing my own yard. But it's a big yard and had become an arduous task due to my photosensitivity and (IBD-related) struggles to remain hydrated. At the urging of one of my doctors, and my wife, I finally gave that up. I miss it, and hope to resume it once we have a smaller yard, but don't miss feeling sick for days afterward.
Like DaMa, I try to get challenging tasks done early in the day. We do a lot of the obvious things often mentioned in these discussions: cook in batches, eat a lot of leftovers, and the freezer is always well-stocked. (So are household supplies, to cut down on unplanned trips to the store.) All my prescriptions are set to automatic refills so I never miss a dose of medication.
Realizing how much better I felt physically after giving up on mowing made me reassess other household tasks. I ended up buying a cheap, older model Deebot, and now on days when I'm exhausted or my arthritis is terrible I let that clean up the pet fur on our hardwood floors.