The only way to find comfort in a sentence like that is to experience an utter revolution of what you count as most valuable. Fear is what you feel when your greatest values are threatened. Confessing my name before men is more valuable than life. When you set out to follow Jesus you surrender earthly life as an ultimate value. And in its place you put the life of the soul in God.
Eternity is far more important than time on earth.
Hell is more fearful than suffering for Christ on earth. Union with God is more desirable than all the pleasures of earth. You can only be killed. The fourth and final argument for why we should not be afraid is found in verses 29-31. God's will for us is our good.