When you have kids and you are in your 40s you are spending lots of time being a parent and honestly eating a lot of crap they eat.
Fitness-wise that was a bad time for me. It happens. I dead lift well over 300lbs now and turn 700 watts pretty easily on a spin bike at 57. My waist is a 28 and I am 5 10. At 45 I couldn’t run 2 or 3 miles, I never wore jeans and my waist was at least a 34.
As they get older you have more free time and you eat better and get in a fitness groove.
Diet at this point is critical.