I too was 80 this last August. At present I am fit and healthy, but like everyone posting here, my thoughts turn to my demise. I have possibly 5 more good years. I don't smoke, don't drink too much, I eat reasonably healthily and keep fit. I was a long distance runner and recreational runner from the age of 15. I gave it up 4 years ago as my knees were bone to bone. I now walk a lot, particularly around my Mooban in CM, for about 40 minutes after my evening meal. I climb and descent 1,000 stairs a week and I don't worry a lot, just mainly day-to-day concerns.
The question we all need to think about is how and when we decide enough is enough. Do they have assisted dying here in Thailand? Having read this thread through to here, I made a mental note to research alternative easy ways to end one's life. It's worth knowing about.
Finally, I agree 100% regarding your last 3 statements, i.e., wife & daughter's future, Definitely no burden for her to look after me and to take each day as it comes.