I've always been very struck by St. Therese's discussion about getting gifts. She emphasizes that we should accept a gift in the spirit in which it's offered -- and also admits why, even for her (a saint!), this is difficult.
This is the line I especially love: “for the love of God and my Sisters (so charitable toward me) I take care to appear happy and especially to be so.”
If you'd like to watch a short video of me talking about the happiness resolution of "Imitate your spiritual master," it's here: