Whatever you Imagine yourself to Be, you can Become, so be Smart about your Dreams and Goals.
If someone pretends to be happy, they can actually trick their brain into feeling happy, such as smiling even when you don't want to. However it goes the other way too and if you think negatively and imagine yourself to be bad or sad you will slowly become that. It is the idea of a self fulfilling prophecy and it definitely can become a problem so always try and imagine yourself in positive situations and they will seem to happen more often.