Answer:
There's not an easy answer, but one thing is certainly true: it has to come from inside. One way to instill the right mindset for building self-assurance and confidence is to spend time with thoughts that motivate and inspire us.
"Because one believes in oneself, one doesn't try to convince. Because one is content with oneself, one doesn't need others' approval. Because one accepts oneself, the whole world accepts him or her."