Albert Barnes on Acts 20:13

Sailed unto Assos. There were several cities of this name. One was in Lycia; one in the territory of Eolis; one in Mysia; one in Lydia; and another in Epirus. The latter is the one intended here. It was between Troas and Mitylene. The distance to it from Troas by sea was much greater than by land, and accordingly Paul chose to go to it on foot.

Minding himself. Choosing or preferring to go on foot. Most of his journeys were probably performed in this way.

(*) "afoot" "Intending himself to go by land"