Unfortunately, most of us don't exactly do this. I spent a HUGE part of my life online gaming - its not something that people do if they have, say one more month to live. Its a good thing I have stopped active online gaming.
Anyway, from a practical point of view, I can't live today exactly like my last day. I gotta work so I can save up for tomorrow. As the breadwinner of the family, I have responsibilities for the future.
I guess I got to tweak the saying a little.
Live today as if it is my last, and save up as if I will never die.