" The Lord himself goes before you and will be with you; He will never leave you nor forsake you. Do not be afraid; do not be discouraged."
And the last part of the verse" Do not be afraid;do not be discouraged". For what reason should we allow ourselves to feel afraid or discouraged when we have God with us. Our Father who will never abandon us, or leave us. Even when we may feel like we've had enough and it's time to give up, God will be here and He will give us that little push we may need to continue - He never gives up on us.
When you can't trust anyone else, you can trust God.