The aim of prayer walking is to claim every inch of a specified area for The Lord. It is a practical way of saying to the enemy "We are taking your territory for God. We come to plant the flag of God's Kingdom on every piece of ground that we walk on. Your time of controlling this area and these people is over". The physical walking is therefore a spiritual act.
“…I will give you every place where you set your foot…”
Joshua 1:3 (New International Version)