The full quote often reads: "The clock is running. Make the most of today. Time waits for no man. Yesterday is history. Tomorrow is a mystery. Today is a gift. That's why it is called the present."
In the 1902 book, "Sun Dials and Roses of Yesterday: Garden Delights..." by Alice Morse Earle, it is noted that the words "Time Waits for No Man" is a play on words or punning device of "gnomon" that has been used on sun dials. A gnomon is a pointer on a sun dial. Somewhere along the way came the full quote which has been truncated by some to your version.
http://books.google.com/books?id=puICAAA...
Many believe the phrase has its root in "Time and Tide wait for No Man," meaning no one is so powerful that he can stop the march of time.
According to "The Phrase Finder":
The origin is uncertain, although it's clear that the phrase is ancient and that it predates modern English. The earliest known record is from St. Marher, 1225:
"And te tide and te time þat tu iboren were, schal beon iblescet."
A version in modern English -- "the tide abides for, tarrieth for no man, stays no man, tide nor time tarrieth no man" evolved into the present day version.
http://www.phrases.org.uk/meanings/38400...
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Nowhere is this sentiment more artfully expressed than in Emily Dickinson's poem #1292, "Yesterday is History."
Yesterday is History,
'tis so far away --
yesterday is Poetry,
'tis Philosophy --
Yesterday is Mystery --
Where it is today --
While we shrewdly speculate
Flutter both away