I can't explain the causal connection between believing and succeeding, but I know that it does exist in every facet of our lives. The human mind is the most powerful computer created. It has the power to make us successful just by knowing we will be. I don't know if this is true, but it makes sense to me. As humans, we tend to dwell on the negative and not the positive.
Bad news travels fast, so they say.
When trading, new traders tend to become pessimistic when they lose money. They can't accept the fact that losing trades will occur. But losing the battle isn't half as important as winning the war. A trader needs to believe that a losing trade does make a bad trader. Quite the contrary, taking a loss when it is necessary actually is the sign of a good trader.