Our happiness here on earth is an indicator of how happy we will be in eternity. Eternity in heaven is unquenchable happiness and it begins right here.
Happiness is not the absence of pain and anguish, but the Inextinguishable joy we receive in Jesus Christ. This is the joy of having 'found ourselves' in Christ. This very joy is what Jesus displays on the cross. Happiness is to be found in Christ crucified.
Jesus on the cross is not a sad person. Jesus is happy because he is detached to wealth, power, pleasure and honor, the very things in which we seek our happiness. Jesus has nothing to lose but only gains, immeasurable gains. What Jesus does on the cross is growing out of himself, surrendering himself totally to the will of the Father, and embracing what it takes to set his children free, for them to be eternally happy.
To be happy, we must despise what Jesus despised on the cross and love what Jesus loved on the cross.
Jesus said if you want to be my disciple, take up your cross and follow me. Happiest person is a disciple of Christ. The cue to happiness is to be found in understanding how Jesus handled his cross.
Jesus was a happy despite the visible pain, unbearable suffering, unreasonable abuse and the mockery. His inner peace is evident from his reactions. Look at him! He is calm, he is not provoked, he is resolved and he is willing. He prays 'father, may your will be done'.
He is in control. No amount of afflictions take away the joy within him. He is not seeking to be comforted, He is comforting us instead. 'Look mother, I make everything new' He tells his mother. 'Do not cry for me, but for yourselves and your children' He reminds the sorrowing women of Jerusalem.
He not only unconditionally forgives his persecutors, but intercedes for them to the Father ' Father, forgive them, for they do not know what they do'. He wishes them well in the midst of the writhing pain. He knows what he is doing. He said to the thief crucified with him 'you will be with me in paradise today'. He does not curse anyone. He is composed. His joy is inextinguishable.
On the cross, He is in a constant dialogue with the Father. He is concerned about his duties. He entrusts his mother to his disciple John and John, is youngest disciple to his mother. He does everything according to his Father's will, nothing more, nothing less.
And we know that in all things God works for the good of those who love him, who[a] have been called according to his purpose. Rom 8:28