To walk and pray redisposes us for all kinds of things to happen. We may be led to a place or building and claim its use for God. We may pray healing in an area that is knowing great distress. We certainly can pray quietly for people who live and work in that area, even at the same time as we are exposed to new impressions of it. Two walking together gives the opportunity to pray aloud in turn, discreetly giving the impression of talking one to the other. Often God's heart for a place will come upon us under these circumstances, and we become aware of the needs of the people around about, and what can be done to be part of meeting such a challenge.
Sometimes such a walk enables us to be in the path of an event, encounter or difficulty. Praying does not exempt us from involvement -- remember Jesus' story of the man set upon by thieves, and the ones who saw and passed by! Aidan and his companions walked, saying the psalms or reading sacred Scripture as they went, but whoever they met he would challenge to love God more or, of they did not know Him, to believe and be baptized as His follower.
Is this the path we take, a daily and constant walk with God, a never ceasing conversation with Him as go through our daily activities from the time we first rise from sleep in the morning until we lay our heads on the pillow each nigh? If not, how then can we claim to be walking with Him?