@Carol52 you sound very like me (except for the asthma)! What worked for me was:
Clear out your cupboards of any junk
Menu plan and grocery list
Fast800 or Mediterranean diet
Food diary or track with an app
I lost 3 stone in 5 months. No exercise. Lots of veg (steamed greens every day plus roasted veg). Every week I roast a chicken, smoked haddock, wild salmon, (tinned fish is cheap and nutritious if you can’t afford fresh), eggs, lentils, chickpeas, kidney beans, courgettes, mushrooms, cauliflower, leeks, onions, garlic, herbs and spices, roasted tomatoes, steamed spinach, broccoli, kale, Brussel sprouts, purple spouting. I also eat potatoes now I am maintaining.
It can be done but you can’t be half hearted. I feel fantastic age 58 and have recently done C25K as my back finally healed. I am 5ft 6 and weigh exactly 9 stone. Try to frame it as something good you are doing for yourself and not as a horrible task.