My last t had me do a similar excersise but he didn't want me to aim for things that made me "happy". That seems like a lofty goal when you are depressed. No he wanted me to jot down moments in my crappy workday that were more positive than the rest of the day. If I went for a walk and a puppy came up to me that would count. Or the coworker who gave support when another was being s jerk. Or maybe I won something small like a movie ticket. Small moments of sucking less than the other moments.