Its a horrible feeling. The feeling that everything you are doing is pointless. You know when I feel this way most? When everything I am doing is for me and me alone.
  I spend so much time worrying about my goals, my passions, my desires..
When I accomplish these goals what do I gain?
A fleeting feeling of partial satisfaction at best. A pat on the back, a few more dollars in my pocket, a quick buzz. . However, when I see that what I have done brings SOMEONE ELSE joy.. That's a feeling of satisfaction that lasts.. When I know I have truly made a difference, then I feel true joy.
  It makes sense really. It has to for the world to go on. Greed and selfishness lead to self-destruction. Maybe the person benefiting from the greed will gain but others will suffer. The world can not progress unless we are all progressing. We are all on the same team and most of us, at our core, desire the same thing. We all desire to be accepted and to give acceptance. To be loved and to give love.
If you think about it, love is the truest definition of acceptance. For the strongest love that humans can possess is is not the love that is sung about on the radio. That love comes and goes and is based on circumstances and actions of the giver and receiver. The strongest love is an unconditional love. A love that sees the immeasurable beauty of a soul and can't not love... Unconditional love means understanding and accepting every unappealing or inconvenient aspect of a being and choosing love anyway. Its not creepy or controlling its just there. .
And it always will be. This is the sort of love that Jesus talked about having for all humanity. If we could learn to love like that, just think of what our world could be..