If everyone waited to do something good until they had purely unselfish motivations, no good would ever get done in the world. The point is to do it anyway.
To listen is to continually give up all expectation and to give our attention, completely and freshly, to what is before us, not really knowing what we will hear or what that will mean. In the practice of our days, to listen is to lean in, softly, with a willingness to be changed by what we hear.