Maintaining Focus

It seems that with the warmer weather here in Michigan that student spring fever as also come early. Usually students hold out until at least the end of March to begin to pine for the summer. So how do we as teachers maintain their focus?
  We can threaten. What teacher hasn't told a senior over and over that even if they are already accepted a college can take that back if they completely fail their last semester in high school? I have. I've ruined kids summer dreams by telling them that there is no beach anywhere near the summer school campus. Ive told students that their grades are on that fine line and these last weeks will mean a letter grade. I've lied through my teeth to get them to focus.
  We can bribe them. On those nice warm and sunny spring days you get them to focus by telling them they can go out early.
  But can we instead simply compel them? Can we create a better inside? While this might be the goal of a teacher year round these coming months might be the most important.
  While observing a teacher a few years ago (during this same spring fever) I noticed that he worked to play off the students. They wanted to go outside then they had a lab outside. They didn't want to read the chapter then instead they talked about the topic (he was very good at sneaking in the vocab terms). The work of making his class compelling revolved around a continued bounce back and forth from his plans and their behaviors. I found this to be very important. That teacher could have spent hours creating an experience but if the students were;t in the mood then all was wasted. Instead of trying too hard to create ahead of time he taught me to react to their demands.