(Thanks to Paul Douglas Boyer for the basis for this little summary)
...it is possible to invest without fretting over the ups and downs of the market.
A passive or indexing approach to investing involves concentrating on the things that we can actually control—asset allocation, fees, transaction cost and efficiency with which strategies are implemented.
This approach certainly does not offer a quick-fix and it does not carry any of the seductive qualities of gambling or day-trading. It not offer the sizzle that the media likes and if you are looking to investing to provide an adrenaline rush then you should be looking elsewhere.
Like most things of value in life passive investing takes discipline and time to reap the rewards. The process is based on a solid academic foundation of empirical research and it is the most intelligent and prudent way to build wealth over the long run.
Your investments should not be a cause of stress in your life.
By understanding this approach you will recognize that it offers the most sensible investment solution.