It's kinda difficult to explain in a short reply format. Try googling "walking meditation" and researching how it's done properly. I prefer doing it vipassana way but there is quite the variation in practice.

Basically you walk at a slow pace in a most non-crowded place while passively focusing on some specific sensation, but not thinking about it or getting distracted by other thoughts and sensations. In my case it's usually the sensation of air during breathing through the nose. If you do get distracted you just gently return your focus back to observing without internal fuss or overanalyzing. Also music and smartphone are a big no there.

This might be worth a dive: https://news.ycombinator.com/item?id=28268136