God is holding you.
The promise of Isaiah 41 is not that you will instantly feel brave. It is that God is with you, strengthening you, helping you, and holding you up.
Scripture · Source
“Don’t you be afraid, for I am with you. Don’t be dismayed, for I am your God. I will strengthen you. Yes, I will help you. Yes, I will uphold you with the right hand of my righteousness.”Isaiah 41:10 · Word of God