I and some of my co-workers started a monthly contest for photography about 8 years ago. I got it rolling because I knew even back then I needed at times to be forced to shoot things that were outside of my interest area.
This POD is one example of a topic. The March 2014 topic is antiquities. This would never be an area I would go and shoot in. It is just not something I am interested in. The thing is with the contest is that it forces you to do things you have no interest in. That is never a bad thing.
Broadening your horizons will just make you stronger at the things you do love to shoot as a photographer. Becoming really good at shooting things you don’t like is the difference between good and amazing. When you become really good at shooting the things you do not like you hone your skills in a different kind of way. That is amazing.