Do you do it, if the 'reward' doesn't equal or surpass the effort required? When/where and why?
Yes! In my personal corner of the world the reward is always in the effort I put forth. I enjoy helping others without expecting a thing in return, whenever and wherever I can.
I was once asked by my brother if you get a reward for going to work. I think he was trying to be funny.
There are many types of rewards, benefiting mankind, spiritual rewards and financial.
Often I have done things for love and expecting nothing in return!