I came across an excellent piece by Ray Dalio (CEO of Bridgewater). The document can be found here: http://www.bwater.com/Uploads/FileManager/Principles/Bridgewater-Associates-Ray-Dalio-Principles.pdf
In relation to investing he wrote the following:
“So in 1975, after a quick two year stint on Wall Street after school, I started Bridgewater. Soon after, I got married and began my family.
Through this time and till now I followed the same basic approach I used as a 12-year-old caddie trying to beat the market, i.e., by: 1) Working for what I wanted, not for what others wanted me to do; 2) coming up with the best independent opinions I could muster to move towards my goal; 3) stress-testing my opinions by having the smartest people I could find to challenge them so I could find out where I was wrong; 4) being wary about overconfidence, and good at not knowing; and 5) wrestling with reality, experiencing the results of my own decisions, and reflecting on what I did to produce them so that I could improve.”