Positive thinking is very good, even necessary, in order to have a hopeful vision of life.Your vision is of enlightenment, and nothing could be more positive. Having found your vision, however, you don't have to force yourself to think positively all the time. That is an artificial way to approach the mind.
I find that if you don't force your mind, it works more naturally and with less stress.
Human nature is divided; it contains both darkness and light. You can choose to accept the darkness and wail on it, or you can choose to expand the light until the darkness no longer dominates by choosing positive thinking.