The Bible exhorts us to take hold of that to which we were called when we accepted Christ that we might fight the good fight of the faith (1 Timothy 6:12). This is the path to confidence - to claim our calling for our own, to hold on to our assurance of salvation, to be intimately aware of the presence of Christ in our lives.
When my confidence is shaky, when I'm not sure what to do or where to go, I am still confident in Christ's love for me. My thesis defense is quickly approaching, and I find myself full of nerves. The what-ifs attempt to undermine my confidence in myself, in my learning, in what God is doing in my life. However, when I take hold of that which Christ has done for me, when I focus on my eternal goals, not just my upcoming evaluation, that confidence comes back.
If I am doing what Christ is asking, and if I am going where He is leading, the what-ifs have no power over me. I am confident that Christ will complete the good work he began in me. I am confident that He will equip me as needed. I am confident that I can succeed as He wills.
Are you taking your confidence from Christ?
Being confident of this, that he who began a good work in you will carry it on to completion until the day of Christ Jesus.