Interesting experience today. Took my children to a local playground. Half mile walk. Had to stop 3 times on the way as I ran out of breath every 250 yards. Sat on a wall or park bench for 30 to 60 seconds and made deep slower breaths. Sat down at playground for 25 min while children played.
Managed to walk home in one go at a normal pace of just under 3mph and did not need a break. Suggests that the metabolism takes some warming up. Tomorrow will take it easy for first half mile then do 1.5 miles more. Only problem I have now is the breathlessness. Before Covid I was pretty healthy and could do heavy manual labour for several days in a row before being exhausted. Don't drink, never smoked.