We are shaped by our thoughts; we become what we think. When the mind is pure, joy follows like a shadow that never leaves.
Are your thoughts filled with joy? Is your first thought of the day one with joy or frustration, joy or disappointment, joy or grumbling? Which do you think would be a better way to begin the day with? When you are filled with joy on the inside, it is naturally going to seep out of you and into others.