“There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” Charles Darwin - The Origin of Species
We are each given one lifetime to explore all the possibilities that the world has to offer. One lifetime is not enough to spend it frivolously on things that don't matter on the long run.
One lifetime is barely enough to just understand everything we want to do, let alone start accomplishing things, never mind getting them done. I strive to start as many things as possible just so I can try to complete a few things by the time I am done living.
There is no great mystery to what life is. It is the time we are given to accomplish things. While alive, we should work hard. Love everything we do. Find things that excite us and cause us to forgo sleep in order to be exhausted in joy. By defining our actions, we define our lives.
When it inevitably comes to an end, don't look back on it. Live fully while alive and then be done with it.