Passion is a driving emotion. Passion can be described as a "ruling" emotion, as well as ferver, or zeal. Passion is a strong desire or devotion to an activity, object, feeling or concept. Passion can be an unwavering pursuit of a goal or devotion to a cause.
In common use, we often talk of passion as a good thing. We talk of people's passions and their pursuit of them as an exercise in free will and "admire" "heroes" such as athletes for their passion.
In awakening, in living in/as/of the force passion takes us fully into egoic drives and desires and pursues them so fully that one cannot hear the force.
Your focus determines your reality, where attention is, there you are. If your focus on on zealously pursuing a desire, devoting yourself fully to that activity/object/feeling/concept, then you are far away from being in the moment, far away from the force.
A Jedi is serene, embodying what the Buddhists call "Upekkha" or Equanimity. Equanimity is one of the four qualities of love. This is not indifference or aloofness. It is an engaged equanimity, a calm serene kindness and caring toward everone with kindness flowing toward all in all situations and relationships. This is serenity that is calm, with kindness, in all situations, but especially under stress; balanced and flowing from the force. "