I still have two more difficult exams left, but I'm trying to ________ ;after these I won't have any more for a year!

The idiom 'looking on the bright side' refers to being optimistic about the nature of things, i.e. not focusing solely on the discomforting part of something. The discomforting part that the sentence presents to us is that two exams are left. Still, we go on to rather discuss 'after these, I won't have any more for a year', and therefore are optimistic; it can thus be said that we are 'looking on the bright side' of things.