It all boils down to the fact that the human body wasn't engineered to sit / lay down 23hr/day.
Start moving, go for walks, do some calisthenics at home, buy some resistance bands for home workouts, get a stationary bike, anything is better than nothing.
Depending on your kid(s) age, go to the swimming pool / parks / hikes / bouldering gym / &c. with them.
> 8 to 10 hour a day dev here
Cut that to a healthier amount.
Run. It's cheap, simple, progressive and it's basically what humans have been optimized for.
Beware of running on concrete if you are overweight, it can worsen back problems.
Swimming is better as it exercises the whole body but it's not that easy if you don't have a swimming pool nearby, so it gives you a lot more excuses.
Walk part of your commute. Do something active with your kids.
I believe there will be no way for you to start a normal training routine right away. You can start with daily 7 minutes workout ( https://www.webmd.com/fitness-exercise/a-z/seven-minute-work... ), that should create a small habit, and later you can build on that.