One major key to overcoming insecurity is to meditate on and speak positive things about yourself.

Our thoughts and words about ourselves are tremendously important. We need to mediate on good things about ourselves - on purpose. We need to look for good things about ourselves, think on those things and speak them to ourselves.

If we talk about ourselves in a negative way, we begin to see ourselves in a negative way. Soon we begin to convey that negativism to all those around us. It is literally true that others' opinions of us will never rise above the opinion we have of ourselves.
If I am around people who are confident and convey that confidence, I find I automatically have confidence in them. But if they convey to me that they don't believe in themselves, I find it very hard to have confidence in them.

That same principle applies to us. If we want others to have confidence in us, we must show them we have confidence in ourselves.

Source: Help Me I'm Insecure by Joyce Meyer
Excerpt permission granted by Harrison House Publishers