Are you living or existing?

Another thought provoking questions from super dad, Marc Pickett:

I've been pondering this question a lot lately: What is time well spent? In his essay on the shortness of life, Seneca says "Life is not short, but we make it so... The amount of time we really live is small. The rest of our days are spent just existing."

From this, I ask myself "What is time spent living vs. time spent existing?"

Or more pointedly, "What is time well spent?"