Source: The Secret of Invincible Joy by John Piper
Jesus revealed a secret that protects our happiness from the threat of suffering and the threat of success. That secret is this: Great is your reward in heaven. And the sum of that reward is enjoying the fullness of the glory of Jesus Christ (John 17:24).
He protects our happiness from suffering when he says,
Blessed are you when others revile you and persecute you and utter all kinds of evil against you falsely on my account. Rejoice and be glad, for your reward is great in heaven. (Matthew 5:11–12)
Our great reward in heaven rescues our joy from the threat of persecution and reviling.
He also protects our joy from success when he says,
Do not rejoice in this, that the spirits are subject to you, but rejoice that your names are written in heaven. (Luke 10:20)
The disciples were tempted to put their joy in ministry success. “Even the demons are subject to us in your name!” (Luke 10:17). But that would have severed their joy from its only sure anchor.
So Jesus protects their joy from the threat of success by promising the great reward of heaven. Rejoice in this: that your names are written in heaven. Your inheritance is infinite, eternal, sure.
Our joy is safe. Neither suffering nor success can destroy its anchor. Great is your reward in heaven. Your name is written there. It is secure.
Jesus anchored the happiness of suffering saints in the reward of heaven. And he anchored the happiness of successful saints in the same.
And thus he freed us from the tyranny of worldly pain and pleasure.