See other people smile

One kind of happiness that I really love to witness is when someone celebrates other's joy. 

For me, that's one of the purest and most genuine form of happiness—witnessing someone's triumph, but doesn't get any feeling of being envious about it. Instead, they see themselves in foresight having the same situation and moment; never losing hope that one day, it will happen to them. 

They see it as an inspiration to thrive on this life, not as a reason of jealousy that will cause them to belittle themselves.