There was a chassid named Reb Peretz, who was a pious and committed Jew. When he prayed he would cry from one eye and smile from the other. His friends asked him, "How is this possible?" He replied, "The joy comes from meditating on G-d's greatness, and the tears come from contemplating my own deficiencies as a mortal being."
Hapiness doesn't always mean smiling and laughing. To be truly happy includes crying from time to time. (Rabbi Chaim Dalfin, Your Better Self)
BS"D - בסיעתא דשמיא