Scott Adams said this quote

It’s tempting to imagine happiness as a state of mind caused by whatever is happening in your life. By that way of thinking, we’re largely victims of the cold, cold world that sometimes rewards our good work and sometimes punishes us for no reason. That’s a helpless worldview and it can blind you to a simple system for being happier. Science has done a good job in recent years of demonstrating that happiness isn’t as dependent on your circumstances as you might think. For example, amputees often return to whatever level of happiness they enjoyed before losing a limb. And you know from your own experience that some people seem to be happy no matter what is going on in their lives, while others can’t find happiness no matter how many things are going right. We’re all born with a limited range of happiness, and the circumstances of life can only jiggle us around within the range. The good news is that anyone who has experienced happiness probably has the capacity to spend more time at the top of his or her personal range and less time near the bottom.