Without confidence it is not possible to achieve much in other streams of life. In the equity markets, it is doubly true. If you lack in self-confidence, doubts may creep up in your mind. This may lead to indecision, which in turn lead to missed opportunities and losses. For day-trading and short interval trades, confidence is of utmost importance.
On the other hand, on down days be careful. In many instances, you may be tempted to book small profits just to make your day balance sheet look pretty. This is not the issue. When you are faced with loss-making trades sooner or later, that same daily balance sheet will not look pretty at all.
Never be far away from the correct principles of trading no matter what your mind is tempted to think. It is just too painful to reinvent the wheel.
In order to be a successful investor/trader, you must be very disciplined. Stick to the plan of action. This means that you will stick to trading policies, trading plans and so on. Know your objective and work accordingly.
Do not seek to implement new ideas that come all the time during markets. Remember, ideas are just ideas. If you feel there is value in them, they have to be thought about, refined, tested and then brought to the trading room. If you try to implement new ideas immediately to trading all you will do is to erode capital and confidence.
Do not allow hope to loiter anywhere close to your trading system. Hope has the potential to do maximum damage to your capital.