One of my favorite quotations has always been "Don't ever say, 'I don't have enough time.' You have exactly the same number of hours per day as William Shakespeare, Marie Curie, Thomas Jefferson, etc."
The original quote is probably untraceable and the names change through time. Current versions seem to feature Bill Gates and Oprah.
I try to live this quote. I talk a lot about being busy, but I will almost never say "I don't have enough time." Time is a choice.
That said, my friend Jim sent me this lovely link on Jefferson and the passage of time.