This is a great opportunity for you to rise above those co-workers. Do more than what is expected of you and shine that happy attitude. In the end I believe it does pay off and you will be recognized for it.
In every work place I have found others that I didn't understand how they could possibly hang on to their jobs by their actions. It never ceased to amaze me. I used to spend way too much time worrying about them that I lost focused on what mattered, the job...
Hang in there and stay focused. Praise yourself if nobody else does.
