"The happiness of your life depends upon the quality of your thoughts: therefore, guard accordingly, and take care that you entertain no notions unsuitable to virtue and reasonable nature."
"Happiness is the meaning and the purpose of life, the whole aim and end of human existence."
"So much sadness exists in the world that we are all under obligation to contribute as much joy as lies within our powers."
"Happiness is a conscious choice, not an automatic response."
"We all want to be happy, and we're all going to die. You might say those are the only two unchallengeably true facts that apply to every human being on this planet."