Research into short-term trading indicates that taking advantage of the market's tendency to become overextended, regardless of direction, is the easiest, most effective path toward success as a trader in equities and the stock indexes that they compose. The trading system or method presented here -- the RSI(4) less than 25 -- is in reality one of several systems that are successful trading the E-mini S&P 500. The system also has another important quality: a high winning percentage. Trading systems with high win rates and minimal draw-downs are simply easier to stick with because the sensation of trading -- the day-in, day-out experience of placing orders, getting into positions and exiting them -- is largely positive. But what is almost more important than the method itself is the understanding about how markets really work that simple, effective trading strategies like the RSI(4) less than 25 provide.