Your fitness level really affects how much activity you find tiring. I remember back when I was a teenager working at a grocery store I freaked out because I saw a woman dripping with sweat and panting (I was worried it was a heart attack or other medical emergency) and she explained that she’s fine, she just decided to walk her shopping instead of getting a motorized cart today.

Or for a more personal anecdote, I got on my bike for the first time in a decade early last spring and barely made it one block on the bike before being at the nearly-vomitimg-from-over-excersion point then by biking every day I got up to biking 8 miles a ride by the end of fall

You don’t have to be tired for it to be exercise

when you spend most of your time in a relatively sedentary lifestyle, walking a mile can be a lot of exercise. for someone who wants a minimum of 12,000 steps a day, it seems like nothing, but for someone who averages maybe 1000 steps, it can take a lot of physical and/or mental effort. especially if that person is dealing with chronic pain or depression

OOP did mention chronic pain, so to them it probably is.

Yeah, same. Its remarkable tbh