Fear not, for God is with us

There are various passages in the Bible that advise us not to be anxious or fearful, but rather to trust in God. For example, in John 14:1 (ESV), Jesus says

Let not your hearts be troubled. Believe in God; believe also in me.

Again, in Philippians 4:6 (ESV), Paul says

Do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God.

 In Isaiah 41:10 (ESV), God speaks through Isaiah saying

Fear not, for I am with you;
    be not dismayed, for I am your God;
I will strengthen you, I will help you,
    I will uphold you with my righteous right hand.

Those passages don't promise that life always will be easy. Those passages don't promise that we'll avoid difficult times. But much as Moses advised Joshua, we should realize that God can do anything, so we should submit to him. Believe in him, trust in him, and then leave the consequences of life to him.