We tend to overestimate what we can do in a short period, and underestimate what we can do over a long period.
Gretchen RubinYour unhappiness doesn't help anyone else - and in fact, as I mentioned in another answer, happy people are more altruistically inclined. So happiness is not a selfish goal.
Gretchen RubinA book is a better way to develop a complicated idea, or to tell a big story and to show how ideas weave in and out of each other, which is something that comes up a lot in happiness because all these ideas are interconnected.
Gretchen Rubin