I have been working on my MA in English with a focus on TESL (Teaching English as a Second / Foreign Language) for the past 2.5 years. I plan to become an English instructor and maybe an aviation ground instructor at a local community college. Yes, it will be a pay cut but I am so burned out with the uncertainties in my schedule, crappy cold wx, early morning min. rest, and airlining all over the place as a fractional pilot. I also have lost all motivation to pursue an airline career and if I get the flying itch, I plan to just rent a C172 on a nice weather weekend.
So my suggestion is to find something that interests you and use your standby time or days off to study and get some credentials for your new career. There was another guy here on the forum who pursued his CPA and left flying to be an accountant. I think anything finance is a good career move, something you can do well into your sixties and perhaps into your seventies. If you want good initial pay, become an actuary. As for me, I plan to work as long as I can to stay active physically and mentally, just not flying.
Hope this helps.