Thirty minutes, the same route, no destination. The daily walk asks for nothing but a pair of shoes and a door to step out of, and it gives back more than most habits that cost money or discipline. It is the simplest thing a man can do for his head and his body, and the easiest to leave for later.
It works because it is slow. At walking pace the mind loosens, and problems that sat knotted at the desk come apart somewhere between the second corner and the bakery. The body gets steady, low work without the soreness of the gym. And the route becomes yours: the cracked kerb you step over without looking, the dog behind the same gate, the old lime tree whose roots have lifted the paving slabs.

how to make it stick
Go at the same hour every day, ideally after a meal, whatever the sky offers. Leave the headphones at home; the point is to hear the street and your own thoughts. Wear shoes with a firm sole and a little give in the heel, broken in until the leather creases where the foot bends, and a coat that sheds rain without rustling. Keep the route short enough that you never argue yourself out of it. Rain is not a reason to stay in. It is simply a different walk.
After your next meal, leave the phone on the table, put on your shoes and walk once around the block.