I don't believe that's the lesson to take away. I believe one should become and be a person who is happy to take a small part of one's time and share it with others. Taking the time to become that person is the reward.

Being genuinely interested in others is a skill that one can develop and will serve one well, but being useful is not the point.

The point is to take opportunities to be a better person and make the world a better place. My opinion, and you may disagree, but I like myself better by making these my goals.