Constant vigilance. (It's less grim than it sounds.)
I don't eat past the point at which my appetite is sated. I'd probably make an exception for a very special event but it wouldn't be >4 times a year at most and probably only x2.
I don't exclude any food groups but, that said, I make sure that I enjoy what I eat and am well-nourished by it. By default, I no longer eat bread, pasta, rice, or typical confectionery. I eat a lot of fish, vegetables, mostly low-fat dairy like yoghurt but some delicious full-fat such as aged cheese.
I'm as active as practical given several long-standing joint problems etc. from congenital conditions, various accidents plus psoriatic arthritis etc. It's non-negotiatable and not optional that I'm active every day as I can lose mobility, muscle mass etc. very quickly and the women in my family are prone to osteoporosis at a relatively young age.
If I have surgery or need to rehab. from an accident/injury, I never give myself any slack on the physiotherapy or physical rehab. and get back every bit of range of motion that I can.
Body fat level 20% (DXA scan) - which puts me in the 2nd centile for my age-group but is the body composition that is best for my amount of lean body mass.