Confidence is a state of being clear-headed either that a hypothesis or prediction is correct or that a chosen course of action is the best or most effective.
Confidence is built on accomplishment. If you achieve small and big goals, you're going to feel much better about yourself.
Here are 10 ways to build confidence:
Surround yourself with positive people.
Take care of your body
Follow through on the commitments you make to yourself
Monitor your progress
Take credit for your achievements
Find time to do what makes you happy
Think long term