During his Thursday morning Mass, Pope Francis talked about vanity. He explained why it's critical for Christians to not give into this temptation.
"How many Christians live for appearances? Their life seems like soap bubbles. The soap bubble is beautiful, with all its colors! But it lasts only a second, and then what? Vanity is a liar, a fantasist, it deceives itself and it deceives the vain, because in the beginning they pretend to be something they're not and ultimately the vain believe it. They actually believe it. Poor thing!”
The Pope also added that when a Christian does penance, it must be done with joy.
Summary of Pope's homily