You are right, doing something expecting a reward, or out of fear, is not the right thing to do. It is just so hard for me to accept it is inevitable, or that changing our inside world will have no effect on the outside world. For many, many years I saw images in my mind of this planet, destroyed, abandoned, burnt down. Red from the fire, black and grey from the ashes. Some how, it felt that I saw this to remind me of one of the reasons I'm here now , to help prevent this from happening. But perhaps Russel Brand is not the only one with a "Messiah-complex'.
Yes, I can see, there is an enormous lack of balance, there is so much cruelty, so much harm done to this planet and all the life on it. I often felt I hated people for doing what they are doing, for their stupidity (as I perceived it). And yet, I also feel a lot of love for this planet, and for all these billions (including myself) experiencing living here as souls in a human body, with all its challenges.
In the end, yes, to be all that we can be is what is most important. Letting go of attachment and the desire to achieve a certain goal. Just let go....