Take my words for what they are but I knew a man that lived pretty much like Reacher when I was a kid and the man was pretty fit and muscular, only lean.

The man would travel from place to place, doing odd jobs, working in the fields, picking fruit, doing welding and metal working jobs, etc.

He was phisically fit. Not muscular like this actor but his body showed strenght. You could see the muscles contracting under his skin when he applied force to something.

He stopped by my grandparents village one summer and stayed for about a month, working in the fields. One day some neighbour asked him to chop down an old tree and cut it into chunks to dry for firewood. He use a single axe to do the job. Every time the blade hit that old trunk it felt as if the ground shook.