Steven, I don’t have the answer but I will speculate.
Part of it may be ‘waiting for the other shoe to drop’. You know the things to look for and know that they will come to pass, but the ‘when’ and ‘how’ are out there in the future like a specter with a scythe. You have no idea if he is close or how fast he will come.
Humans mentally try to estimate our end. But, as someone who just turned 70 and is most likely closer to the end than the beginning, and is aware that I am physically and mentally ‘different’ than I was 10 or 20 years ago, I can only adapt to what is now. If I plan too far, I may ‘fail’ by being cut short. If I don’t plan far enough, I ‘win’ but have to do it all over again.
Your burnout is understandable. You are carrying a weight that other 44-year-olds aren't.
The best I can say is live life to the fullest that you can.