Biblical view of happiness: hope of a glorious eternity

Romans 5:2 says, Through our faith, Christ has brought us into that blessing of God’s grace that we now enjoy. And we are very happy because of the hope we have of sharing God’s glory.

Let's direct this verse:
I believe that the blessing of God's grace that we enjoy now refers to the forgiveness of sins (because Jesus died and rose again), God's daily help and guidance through his Holy Spirit, and the peace that he gives. We enjoy these blessings because we have faith in God, we believe in him. God's glory that we will share in refers to the fact that we will be in his presence one day. The hope that Paul talks about isn't wishful thinking, the Phillips paraphrase of the Bible refers to it as happy certainty.

Here is Romans 5:2 in my own words: Because we believe in God, we enjoy his grace - forgiveness, comfort, guidance and peace. And we are happy because we know we will  spend a glorious eternity with him.

Here are some other Bible verses about God's promise of eternal life with him:
1 John 2:25
This is what the Son promised us—eternal life.

1 John 5:13
I write this letter to you who believe in the Son of God. I write so that you will know that you have eternal life now.

John 14:1-3
Jesus said, “Don’t be troubled. Trust in God, and trust in me. There are many rooms in my Father’s house. I would not tell you this if it were not true. I am going there to prepare a place for you. After I go and prepare a place for you, I will come back. Then I will take you with me, so that you can be where I am.

The thought of spending eternity with God is a great reason to be happy.