Don't over complicated it. Just get out the door and run some. Start with 3-4 days a week. Go for 20 or 30 minutes or whatever feels good.
After a month or so, you'll know what the next steps are.
My one piece of advice coming back, though, is do less than you think you're capable. Keep some miles and seconds in the tank. It'll keep you hungry and healthy.
Good post. The older you are the more it makes sense to do "less than you think you can."
Actually doing "more than you think you can," in distance running makes no sense at all when it
comes to training. (Race goals---yes, think positive. But training goals should be incremental)