You can definitely regain the oomph!
(This isn't meant to sound lectury, by the way - these are just based on my experiences)
Health - lower carbs, more veg and protein. Absolutely have treats.
Home made cakes with less sugar are lovely and without icings they can be frozen
Exercise - join a friendly club and commit those hours to fitness - twice a week to start with, and you'll get to meet others
Couch to 5K - maybe you could do this when the kids are at school in the mornings? One session takes about 30 mins, give or take.
You don't have to run three times a week - just once a week to get you started.
Hobbies - essential imo - just one thing that you love doing - again, dedicate a couple of hours a week to it to begin with.
Revise your weekly timetable so you can feasibly fit all this in
Alcohol - you don't drink. Neither do I. Best decision I made to go tee total
Post fifties here too, btw, and feeling like i'm early forties 
I hope some of that helps 