“Joy of life seems to arise from a sense of being where one belongs. ... All the discontented people I know are trying sedulously to be something they are not, to do something they cannot do.” -- David Grayson
Being Happy is really a choice. Often it involves previous choices. The choice that you made about “this or that makes me sad” or When that happens it is bad, etc. You created all the rules in your life. Whether you did it consciously or not, you are the one who either made them up or accepted what other people told you.
Which means if you want, you can change your rules. Certain things don’t have to make you sad. You don’t need to have X before you are happy. You can just be happy. And you can be happy and still go after goals in life.