The Wisdom of Life (Essays of Arthur Schopenhauer, tr. T. Bailey Saunders)

Their wordsHealth outweighs all other blessings so much that one may really say that a healthy beggar is happier than an ailing king.

Their wordsCheerfulness is a direct and immediate gain,—the very coin, as it were, of happiness, and not, like all else, merely a cheque upon the bank; for it alone makes us immediately happy in the present moment, and that is the highest blessing for beings like us, whose existence is but an infinitesimal moment between two eternities. To secure and promote this feeling of cheerfulness should be the supreme aim of all our endeavors after happiness.

Their wordsFor the more a man has in himself, the less he will want from other people,—the less, indeed, other people can be to him.

Their wordsThe truth is that the value we set upon the opinion of others, and our constant endeavor in respect of it, are each quite out of proportion to any result we may reasonably hope to attain; so that this attention to other people's attitude may be regarded as a kind of universal mania which every one inherits.