To achieve happiness, first change your state of mind.
Happiness is determined more by one’s state of mind than by external events. Whether you feel happy or unhappy at any given moment is determined by how you perceive your situation and how satisfied you are with what you have. This is the reason why someone who is HIV positive can feel overall happy, and someone who is extremely financially successful can feel overall unhappy.
Change your state of mind—look at the positive side of life—and you will begin to be happier.