To build confidence and self-esteem, look at what you have achieved. Write down everything you can think of and keep on going. Small achievements, minute details that made a difference for which you can tell yourself “well done”. How does it feel, recalling the details? It must surely give you boost just by thinking of them. Next time whenever you feel low on confidence read your list again. You can continue to add your achievements every day if you like. Enjoy the success you have already achieved and believe that you can achieve it again
Think whether your thoughts about you are positive or negative. Stop thinking negative about yourself. Every time you make a mistake, you may find yourself automatically thinking “How stupid of me!” or “Why did I do that?”. Instead, you might say to yourself “Everyone makes mistakes” or “I messed up while playing a game this time, but I helped my team win the last several games.” Once you start thinking positive, start acting positive. Believe in yourself even if you don’t know how to do.

You need to know both the good and bad things about you. Know your strengths and weakness. Next work on the weakness and change them. Know yourself and you will win all battles. If you do not know yourself, you have little chance of knowing anything else. Are you aware what your aspirations, dreams are. Understand what you are passionate about, what you are good at. Keep building and working on yourself.
Set for yourself small goals and try to achieve it. Little achievements make you feel good, and they add up to big achievements. Continue to learn from your experience and from your failures what needs to be improved. Small actions each day will give you opportunity to see progress.
Make it a habit to work on yourself. Taking care of your body can be another way to boost confidence. Engaging in exercise you enjoy, such as swimming or cycling, can also help you feel better and more confident about your body
If you look confident and act the part you aspire to reach, you’ll not only feel in control, people will have much more confidence in you as well. Show confidence in your body language and dressing sense. Keep your spine straight while walking or sitting. Be aware of your gestures. Pay attention to your hands and legs. Always keep a smile on your face. Give a warm handshake. A person in authority speaks slowly, this shows confidence.