I teach a weekly, bible study and have become blatantly aware that 8 out of 10 women suffer with insecurity. We all struggle with "not measuring up" at some point in our life; but many people suffer from insecurity on a daily basis. Whether, we were told by a parent, a spouse or other circumstances we sometimes take on a belief; no matter how hard we try, we aren't enough.
God covers this topic in Ecclesiastes. Soloman, the King of Israel, who had everything (wisdom, power, riches, honor, reputation, God’s favor), was the one who discusses the ultimate emptiness of all this world has to offer.

In Chapter one of Ecclesiastes, he gives the purpose of the book:
To make people realize that their confidence in their own effort, abilities and righteousness is meaningless.  Instead, our commitment to God is the only reason for living; that is our purpose. When we seek Him and fear Him (respect and stand in awe), we become more secure in Him.

Security comes when we start to understand who we are “in Him”. It’s not what we know, or how good we are, or what we possess.

Our security comes from Him; when we are planted in Him we get a trust and a confidence that no matter what happens, we are and we will be okay.

Allowing God to be first and the director of our life, permits us to rest and to be secure in Him; not our own ability or our stuff; all that is temporary.

We get to the secure place in Him through our walk with Him.

Scripture to support this thought:
Ecclesiastes 1:11-4
Ecclesiastes 3:11
Matthew 6:33
John 15:4