As we become increasingly un Christian our society is becoming increasingly joyless.
What are the symptoms of this lack of joy? Worry. Being offended. Being the victim. Anger. Blaming others. Rage. Sarcasm. Mocking others. Self righteousness.
Then there is false joy. The false joy is the laughter and amusement that comes from mere entertainment or worldly entertainment.
True joy, however, is an outward evidence of an inward grace.
It is an outward expression of an inner peace.
It is an outward lift that comes from an inner confidence, and that confidence comes from a deep, unshakeable trust in God and his goodness.
Living in this goodness is living in the Divine Love, so when this happens those who meet us are in touch with an eternal dimension.
When joy is evident it is very, very attractive.
We evangelize best by attracting others to Christ, and if Christ is evident in our lives through joy then others will be drawn to him through his joy in us.
For further reading go back to Evangelii Gaudium