If an individual has been trading stocks or commodities for even a relatively short period of time, then he/she should be well aware of the fact that psychology and discipline are the weakest links in the trading chain. No education and trading would be complete without a discussion of the most important aspects of psychology and discipline. This provides tools that one requires to put the methods and systems that have discussed into action. This chapter discusses the psychology and discipline of trading. Traders and investors are always struggling with the demons that denigrate performance or that cause loss of money. The best trading tools are useless in the hands of an undisciplined trader whereas a mediocre or ‘ugly duckling’ trading approach can be transformed into a money-making swan.