Actually, there was a time, when I thought I could control everything in my life. I had allot of confidence, was a very positive, goal oriented person. Then there came a point, where no matter how much confidence I had, and efforts I made on my own, I was defeated. It wasn't until I was literally on my knees, crying out to God, that things changed for me. It was after this I was able to continue to move forward in my life, because, The Spirit of God gave me strength. I then could step out with a new confidence. I know for some it is hard to understand, unless you have experienced this.
When I'm unsure if I can achieve something I want to do, I observe and study how others do it and then convince myself: "If they can do it, so can I". Confidence then is the firm belief in one's own capability.