To borrow from Henry David Thoreau:

I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived. I did not wish to live what was not life, living is so dear; nor did I wish to practise resignation, unless it was quite necessary. I wanted to live deep and suck out all the marrow of life, to live so sturdily and Spartan-like as to put to rout all that was not life, to cut a broad swath and shave close, to drive life into a corner, and reduce it to its lowest terms.

I haven't gone into the woods, nor have I lived so sturdily and Spartan-like, but my purpose is to come to the end of my life and discover that I have lived. That I have sucked out all the marrow of life. And in the process, to have left the world a little brighter than when I found it.