Cynicism blocks light; it tries to erase smudges of hope about any situation by mocking it, or mocking those taking action on it. Cynicism also breeds laziness because it gives you excuses not to try anything because you've already given yourself an excuse that nothing is going to work.
I try to overcome my cynicism by opening myself to more hope. In concrete terms, I listen to people who are hopeful and doing something to make their situation better. I try and stop watching sad news (or any news, to be fair) on TV or the web. It is for the same reason I block people who post images of maimed or dead people on Facebook, asking me to pray that such things won't happen to me. I watch comedies, listen to funny stories. I try to laugh. That way, I'm able to psyche myself off my butt to do something, instead of complaining or just laughing about it.