3 years ago, I decided to lose some weight and try to get fitter (I had been overweight for many years since becoming office-bound). I was 54 then, I changed my breakfast to fruit and fibre, but I think the secret here is (and this sounds crazy) smaller bowls and plates, we eat with our eyes, and using smaller crockery makes it look like you have more food so you don’t tend to pile it up as much. I also halved my lunch (always have prepared it myself) 1 sandwich instead of 2, a small bag of baked cheese crackers, no chocolate but added much more fruit bananas, apples, etc. Still had a “proper” dinner but just less. I also took up cycling (bought a semi-decent bike - around £300) and used to cycle 10 miles 3 times a week, luckily I lived near a canal then so no risking my life on busy roads.
I lost 2 stone over the period of 6 months, and still drank alcohol as I did before (maybe 5-6 pints a week) and on Fridays would have a pizza and a chocolate bar as a weekly treat, and have managed to keep it off , although I am much more cautious of what I eat and drink, but have got used to the smaller portions.
The old adage “eat less - move more” stands true.