"If I am able to remember loneliness during joy, I might be able in the future to remember joy during loneliness and so be stronger to face it and help others face it. In 1970 I felt so lonely that I could not give; now I feel so joyful that giving seems easy. I hope that the day will come when the memory of my present joy will give me strength to keep giving even when loneliness gnaws at my heart."
--Henri Nouwen, The Genesee Diary: Report from a Trappist Monastery
This reminds me of the second part of my Second Splendid Truth about happiness. Everyone recognizes the first part, but I think the second part is more elusive:
One of the best ways to make yourself happy is to make other people happy;
One of the best ways to make other people happy is to be happy yourself.
As Nouwen says, when we feel joyful, giving to others seems so much easier. So if it is selfish to try to be happy -- which is something many people argue, and which I believe is the biggest myth about happiness -- we should be selfish, if only for selfless reasons.