For the Lord your God is a merciful God, He will not fail you, or destroy you, or forget the covenant of your fathers which He swore to them.
Deuteronomy 4:31 AMP

The God who made and keeps this promise (Israel still exists in spite of all efforts to destroy her) is the same God who keeps this promise to those who believe in and follow Jesus the Christ.

And just as Moses lifted up the serpent in the desert [on a pole], so must—so it is necessary that—the Son of man be lifted up [on the cross]; [Num. 21:9.] In order that every one who believes in Him—who cleaves to Him, trusts Him and relies on Him—may not perish, but have eternal life and [actually] live forever! For God so greatly loved and dearly prized the world that He [even] gave up His only-begotten (unique) Son, so that whoever believes in (trusts, clings to, relies on) Him shall not perish—come to destruction, be lost—but have eternal (everlasting) life.
John 3:14-16 AMP

How can we possibly lose hope when we have a God who will continue to forgive us, continue to love us, no matter what, and who desires to give us life that never ends?

Even though Moses gave this talk to ancient Israel, these words apply to us today who believe in Jesus as the Son of God. The words recorded in Deuteronomy remind us of God’s love and promises to those who love and serve him.

Moses had wearied of their constant grumbling and often disbelief and disobedience over the many years he led them in the wilderness. Even so, you can hear the love for them in these words; because God loved these people, so did Moses. He was willing to give his life for them (Exodus 32:30-32.) His willingness foreshadowed the willingness of God's son to give his life to save us.

But it is in the resurrection of Jesus that life and hope becomes possible (1 Corinthians 15:1-59.)

If only for this life we have hope in Christ, we are to be pitied more than all men.
1 Corinthians 15:19

Since Jesus did rise from the dead, we do have hope in this life and for eternity. We all have troubles in this life, sometimes we get so weary we feel we can't go on. When we remember the love of God which never fails, we can pick up ourselves up and move on, living in hope. God always intends good for us. He is the God of all hope.