There are two big reasons that today is the best day for you to invest:

  1. The power of compound interest coupled with a long time horizon means you always want to start earlier than later -- and that means today. 
  2. Today, the market is undeniably cheap compared to its historical norms.

While it's impossible to predict the market's day-to-day movement, and it may well go down tomorrow, it could just as easily go up. Fortunately, at these prices, investors have more of a safety net built in than they can normally expect. 

One of the reasons the market is so cheap today is that big sectors like finance and energy are trading at deep discounts compared to their typical valuations.

Austin Smith owns shares of Halliburton Company and American International Group. The Motley Fool owns shares of American International Group, Halliburton Company, JPMorgan Chase & Co., and Ultra Petroleum and has the following options: long JAN 2014 $25.00 calls on American International Group, short JAN 2014 $20.00 puts on Ultra Petroleum, long JAN 2014 $30.00 calls on Ultra Petroleum, long JAN 2014 $40.00 calls on Ultra Petroleum, and long JAN 2014 $50.00 calls on Ultra Petroleum. Motley Fool newsletter services recommend American International Group, Halliburton Company, and Ultra Petroleum. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.