It's Not Rocket Science, summarized below
All money managers have slumps of one or more quarters and even one or more years. As such, it's important for investors to keep perspective. Investors who focus too much on short-term results will end up making errors; they may sell at the wrong time, or take more risk than they should. One's money manager should be judged on his long-term results, according to Bradley.
This is easier said than done, but essential. During a market frenzy, if investors are getting influenced by their neighbours' stock success stories, this is a recipe for disaster. To be a successful investors, stay the course, stick to your plan, and avoid emotional decisions.