Alone Together, Again
There is nothing meaningful or worthwhile in life, just living until you aren't.  A lot of comments talk about flow or busyness and there is some truth that we find some happiness in adding to ourselves.  That is, in perfecting a skill so that it becomes "second nature."  I'm not entirely convinced; it seems like it's just a way to distract your awareness from the reality of your existence.There is an old Chinese proverb (the beauty of which is probably lost in the butchery of my translation):"Life is like honey-gathering bees, 
After collecting all the honey from myriad flowers, 
They age and their labor leaves them with nothing."