You Need a Little Pep in your Step
Though it sounds ridiculous, faking confidence when you have none will actually give you some! Self-confidence is a perception held by you and others. If you act self-confident whether you feel it or not, others will perceive you as self-confident and be more willing to follow your lead, take you seriously and listen to what you have to say. It's the great paradox where confidence is concerned, almost a "which comes first, the chicken or the egg" situation. Have a little faith in your self and soon you won't have to fake it anymore.
There's no need to fake confidence if you live each day like the day before. All of that is known territory- you've been there, done that. The most direct route to self-confidence is to take calculated risks and examine your results. Will you make mistakes? Absolutely, but those mistakes contribute as much to growing your self confidence as your victories, particularly if you resist the urge to use them to beat yourself up. No one gets it right every single time and to require that from yourself is self-sabotage at its best. Start will small steps outside of your comfort zone and build your confidence step by step.
Stop doubting yourself by default.
We all have that little voice of doubt inside our heads. The trick is to learn when to pay attention to it and when to ignore it. I am a firm believer in "following your gut" and I've had to learn the difference between intuition and self doubt. For me, what works best is to listen to what that doubting voice is actually saying. If its message is mainly lack of belief in your ability or your deservedness, then ignore it and forge ahead. As you gain self-confidence as confidence in oneself and on one's powers and abilities without suggestion of conceit or arrogance. This is exactly what you gain when you fake it, take risks and stop letting doubt control your next move.