Dear SouthP
I think it may have to do with all kinds of combined worry especially from retiring. Been there-done that. I spent a fair whack of time before I retired thinking about it after counselling co-workers that were having a very hard time coming up their retirement. What I realized was that you study for years to get a job or jobs, work for 35 years and and then are thrown off the cliff without a parachute. Or so it seems. Accept that all that is going on in you is normal. You are going to feel anxious, worried about money, about how you will fill your time. It is all normal. Forgive yourself. A few months after retirement you will wonder where you ever found the time to work. Cheers.