Confidence is something you cannot fake. I see many books telling you about power dressing, power talking. Many people practising looking confident, talking confident, acting confident etc.
You see, you may be able to fool someone for a while but you cannot fool yourself.
Real confidence can only come when you have mastered yourself. When you set a goal and you achieve it. When it becomes self evident to yourself, when the evidence to yourself becomes irrefutable, that you can achieve results.
And until you know that; convice yourself that you can achieve results, your confidence will only be skin deep.
The biggest stumbling block is your feelings. Your feelings of laziness, of anger, of fear. The answer is not to deny your feelings, for you need feelings to navigate in this world. The answer is to do the right thing with courage despite your feelings. Think on this.