Attributed to Leo Tolstoy
«"If you want to be happy, be."»
Misattributed
Verdict
It is not in Leo Tolstoy's work
It circulates widely attributed to Tolstoy, but it is an aphorism of Kozma Prutkov ("Хочешь быть счастливым, будь им"), the fictitious author invented in the 1850s by Alexei K. Tolstoy — Leo's second cousin — and the Zhemchuzhnikov brothers. The shared surname explains the confusion.
What they did say
Verified words of Leo Tolstoy
«All happy families are alike; each unhappy family is unhappy in its own way.»
Anna Karénina, parte I, cap. 1 (texto ruso en Wikisource)
«The hero of my tale, whom I love with all the strength of my soul, whom I have tried to portray in all his beauty and who has always been, is and will be beautiful, is the truth.»
Sebastopol en mayo (1855), párrafo final
«For us, with the measure of good and evil given us by Christ, there is nothing immeasurable. And there is no greatness where there is no simplicity, goodness and truth.»
Guerra y paz, t. IV, parte 3, final del cap. 18