Christian joy thus springs from this certainty: God is close, he is with me, he is with us, in joy and in sorrow, in sickness and in health, as a friend and faithful spouse. And this joy endures, even in trials, in suffering itself. It does not remain only on the surface; it dwells in the depths of the person who entrusts himself to God and trusts in him.
Some people ask: but is this joy still possible today? Men and women of every age and social condition, happy to dedicate their existence to others, give us the answer with their lives! Was not Bl. Mother Teresa of Calcutta an unforgettable witness of true Gospel joy in our time? She lived in touch daily with wretchedness, human degradation and death. Her soul knew the trials of the dark night of faith, yet she gave everyone God’s smile.
In one of her writings, we read: “We wait impatiently for paradise, where God is, but it is in our power to be in paradise even here on earth and from this moment. Being happy with God means loving like him, helping like him, giving like him, serving like him” (The Joy of Giving to Others, 1987, p. 143). Yes, joy enters the hearts of those who put themselves at the service of the lowly and poor. God abides in those who love like this and their souls rejoice. If, instead, people make an idol of happiness, they lose their way and it is truly hard for them to find the joy of which Jesus speaks.
—Pope Benedict XVI (my emphasis).