What are the two most difficult things to do in this business? Here they are: (1) Buy early in a primary bull market and then ride the bull market all the way to near its completion. (2) Sell out on a Dow Theory bear signal, and then stay out of the bear market until it's nearly completed.
Why are those two actions so difficult? They're difficult because a bull market tries in every way to frighten you out of its clutches. And a bear market tries in every way to draw you back into its grip. In both situations, both the bull and the bear markets make full use of secondary reactions.