Let me list down a bunch of things that always destroys myself confidence.
1. My relationships with my past girlfriends
2. My receding hairline
3. My speech
4. Rejection from the opposite sexes
5. Comparing myself with other same sexes
Gosh this is really embarassing. But nonetheless i've did some research from this website
http://www.wikihow.com/Build-Self-Confidence Lol...
Ok so in order to deal with it, i've to keep reminding myself that nobody is perfect. Even the most confident people have insecurities. At some point in any of our lives, we may feel we lack something. That is reality. Learn that life is full of bumps down the road.
Be thankful for what I have. A lot of the times, at the root of insecurity and lack of confidence is a feeling of not having enough of something, whether it's emotional validation, good luck, money, etc. By acknowledging and appreciating what you do have, you can combat the feeling of being incomplete and unsatisfied. Finding that inner peace will do wonders for my confidence.
Be positive. even if I don't feel positive. Avoid self-pity, or the pity and sympathy of others. Never allow others to make me feel inferior--they can only do so if you let them. If you continue to loathe and belittle yourself, others are going to do and believe likewise. Instead, speak positively about yourself, about your future, and about your progress. Do not be afraid to project your strengths and qualities to others. By doing so, you reinforce those ideas in your mind and encourage your growth in a positive direction.
Look in the mirror and smile. Studies surrounding what's called the "facial feedback theory" suggest that the expressions on your face can actually encourage your brain to register certain emotions. So by looking in the mirror and smiling every day, you might feel happier with yourself and more confident in the long run.
Fake it. Along the same lines of smiling to make yourself feel happy, acting confident might actually make you believe it. Pretend you're a completely confident version of you; go through the motions and see how you feel