I find that if the purpose of my walk is to go for a walk then I don't take any pictures. The purpose of going out has to be to take a picture, otherwise I lack the focus to see anything that interests me. Also, walking the streets near my home I tend not to notice anything as it is so familiar. With venturing further afield not an option I put my macro (close up) lens on the camera to force myself to look at little things and find something previously unseen amongst the familiar.