One of the reasons why I took up street photography was that I enjoy people watching its been a favourite past time of mine for many years which then encouraged me to pick up a camera and start documenting the things I see. But I can easily forget why I took up this style of photography in the first place and I can find myself getting "Tunnel Vision" by that I mean I can start hunting for that one shot instead of letting the shot come to me.
The action is not always in front of you its going on behind you as well, if you see an interesting street scene move around it see what it looks like from a different angle try a lower or higher point of view and wait for the right subject to walk through. These are the things that I can easily forget about when I have "Tunnel Vision" sometimes it's good to stop and wait.
So when I feel myself falling in to the trap of hunting for that shot I now stand on the corner of a busy street for half an hour i turn the camera off and watch the action unfold in front of me, yes I may miss that shot but what I'm doing is refreshing my photographic eye and I'm still taking images in my head. Basically I go back to basics and start "People Watching" again.