Welcome! You are in much better shape than a lot of folks, including me 4 years ago - and you're much younger.
I suspect you are more interested in health, endurance and fitness rather than strength or appearance. So, with that in mind, why not start off by doing a set number of bodyweight exercises per day (e.g., pushups, dips, crunches, other things that don't need a gym) and taking up some aerobic exercise like running or cycling. And to get you to want to stay motivated, sign up for a 1-mile fun run or, if you are up for a bigger challenge, a 5K run 4 months from now. Run it with your kid(s). You will not want to let them or yourself down and will feel compelled to get in sufficient shape to complete the task.
My 2 cents.