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Make the decision to be a happy person. Yes, a certain event can cause sadness or joy but day-to-day happiness is a result of your personal decision on how you choose to be, not something that others do for you. You can choose to enjoy things during your day; a walk, your work, meeting people... many things. You would feel better and others would truly enjoy being around you and seek your company, a self-reinforcing cycle.
~ Enjoy your work (work for others, school or even housework) and always try to do a very good job. Work gives meaning to your life. Even lowly tasks when performed well make you feel good about yourself. The results accumulate and others will notice that you are capable.
~ Avoid most daily news reports. It is not necessary for you to worry about the tremendous number of things in the world about which you can do nothing.