How to Be Happy All the Time - Yogananda

Happiness consists in making the mightiest efforts to reduce your desires and needs, and in cultivating the ability to meet those needs at will, always trying to smile, both outwardly and inwardly, in spite of every predicament.

Be silent and calm every night for at least ten minutes (longer if possible) before you retire, and again in the morning before rising. This will produce an undaunted, unbreakable inner habit of happiness that will make you able to meet all the trying situations of the everyday battle of life. With that unchangeable happiness within, go about seeking to fulfill the demands of your day.

Seek happiness more in your mind and less in the acquisition of things. Be so happy in your mind that nothing that comes can possibly make you unhappy. Then, you can get along without things you have been accustomed to. Be happy knowing you have acquired the power not to be negative. Know, too, that you will never again become so materially minded that you forget your inner happiness, even if you become a millionaire.

-How to Be Happy All the Time
by Paramhansa Yogananda