You probably know someone who you believe exhibits great confidence. Using them as a role model can be instrumental in finding your own confidence.
What does your role model's self-assurance look like? Does the person make eye contact when speaking to others? Can you see a comfortable ease with which he relates to others? Think about how the person you have in mind looks, acts, and talks.
Perhaps your role model has a great sense of humor. The self-assured person isn't afraid to admit he's made a mistake. He may even gently laugh at himself for his errors.
Now, try behaving like your role model. You truly can live your way into a new way of thinking. If you emulate the person whom you view as confident, you'll be more likely to exude self-assurance yourself.
Even when you're experiencing a challenge and aren't feeling too sure about yourself, try "faking it till you make it." Use your knowledge about how confidence appears and behave that way. Soon after, you'll begin to recognize and connect with your own true confidence.