Though an old adage, it applies to trading in the financial markets more aptly than anywhere else.
A boxer spends hours on end punching his sandbag. A batsman spends his time perfecting his shots. An athlete keeps on practicing his skill till it becomes perfect. Each one of these and many more spend a great deal of time and energy in repeating their craft or art till the effort becomes completely mechanical and like a robot they go about completing the action. Practice has built into their memory such perfection that their skill is manifested with a pristine finesse.
Similar to the above, a trader needs to first educate himself with all the necessary knowledge required to implement and enhance his skill. Time and effort are required to acquire any professional skill and trading is no different.
After completing his education, a trader then goes into the trading arena where he implements his knowledge. With sheer hard work, persistence and patience he is able to identify favourable trade setups. The challenge here for him is to then replicate these setups on a regular basis in order to achieve consistent results.
This consistency can only be achieved if the trader has earlier practiced so much that replicating becomes mechanical and robotic. Like a machine, then, he goes about identifying and executing his trades. Like a machine he then churns out profits and like a machine he creates wealth. No matter what the situation is and no matter how much the pressure, his performance will always remain the same and he will move with grace and perfection.
Practice makes his sub-conscious so competent that hard as he may try, he will not falter or make mistakes. This practice ultimately sets him apart and makes him a professional and an expert.