I live alone too and my health isn't great so I struggle with cooking too.
There are shortcuts of course. The ones I use are
Using ready prepped veggies - carrot sticks, celery sticks, ready peeled and chopped sweet potato and squash that kinda thing
I've recently discovered McCain jacket potatoes. Intended for microwave but I don't have one so I do them in the oven. Only takes 45 mins. Crispy skins, fluffy potato - yummy
Tinned meals - still kinda ready meals really but you can choose healthier options. I like ratatouille and veg curries and chilli
Batch cook - yea kind of the opposite of what you're meaning but it doesn't really take longer to make 4 portions as one. I tend to make things like chilli, casseroles (super easy the way I do it, just throw all ingredients in a Pyrex, bung in oven, hour later all done) then portion into foil trays, label and freeze. Then on days I don't feel like cooking I have a "home made ready meal" just need to add some sort of carb although not always.
No cook carbs - bread, wraps, pita bread, rolls you get the idea.
As a scot soup is practically our national dish, if I'm making soup a batch will do me 6-8 servings