Even if you do not actually have the confidence, you can fake it through your actions and body language. Eventually, people will take notice and respond differently to you, which in turn will actually make you a confident person. You might be wondering how to fake it...well I'll start you out with some tips:
1. ALWAYS walk slow (almost arrogantly) with your head held high (don't ever look at the ground...imagine a string attached from your chin to something right above your head), shoulders back, and STAND UP STRAIGHT.
2. Keep your hands open (i.e. don't clinch your fists)
3. When sitting or standing, take up a lot of space...shy people will let others "crowd" the out of spaces, but confident people take up a lot of space.
4. Look people directly in the eye, and even hold eye contact WAY past what feels normal...this shows you are confident. Imagine the president or some famous actor looking you in the eye and then looking away...just wouldn't happen.
5. Practice and develop a smile that exudes confidence...I like to think of it as a sly, cocky smile...and USE IT A LOT. Everyone finds it easier to talk to people that look like they enjoy themselves and are always having a good time...and all that takes is a smile.
6. SLOW DOWN your movements...this includes walking, chewing gum, talking...everything. Just slow down...
7. Talk LOUD from your diaphragm. To understand this, put your hand just below your sternum (above your belly button) and try to feel it resonate down there when you talk.
8. Don't take shit from people. If someone puts you down, doesn't respond to you, or anything like that, confidently put them in their place. For example, if you are talking and someone interrupts you, stop, look them in the eye, and tell them "excuse me, I was talking and I don't appreciate being interrupted"
9. Don't try to shy away from conversation. There is no reason that you can't contribute to a discussion, you are probably just as much fun as anyone deep down...and you can get excited when you talk, but keep the loud, deep voice, look them in the eye, use inflection and body gestures (not too many though).
10. Give a firm introduction when meeting people...speak up, give a good firm handshake while looking them in the eye, and just say "hey, what's up...I'm (name)"
If you follow these ten guidelines, you will appear confident and actually start to develop confidence in yourself after people respond to you. Most of this can be summed up by saying "act like you have a 10 inch penis
hanging between your legs." Deep down, everyone on here wants a little more confidence, so if you just act like a man in control who has what every other guy wants, you will do just fine.