mbti-notes:

In the most general terms, it can be an introvert problem, IPs more than IJs though because IJs tend to want more control over their environment. For ISPs, the lack of motivation is likely to come from faulty Ni, they will have a tendency to be self-defeatist, to convince themselves that things are not worth doing before even trying. It’s a negative pattern of thought that stops them from getting out into the world and learning new things that could help them out of their funk. For INPs, the lack of motivation is likely to come from faulty Si and its risk aversion, they may struggle to find interest in new possibilities, avoiding situations that make them feel uncomfortable (either because they fear taking a risk and losing what little they have, or they haven’t gotten over some negative past experience). This is looping behavior, so you can read more about tertiary functions. Achieving meaningful goals requires long term focus and commitment of time and energy, and IPs can feel overwhelmed by this fact because they can be too impatient for results or they unconsciously fear failure.

Everyone needs to find the appropriate balance between introversion and extraversion. Introverts who are disconnected from their extraverted functions will feel little to no desire to engage with the world, have no passion for exploration and discovery of new things, and derive no satisfaction from their accomplishments. In short, without healthy extraverted functions, introverts will not be able to find the things that bring them joy or fulfillment in life because they’ve essentially locked themselves into a mental cage, believing that they can be self-contained and utilizing various mental gymnastics to deny the need for growth and intellectual expansion. Of course, there can be a variety of other factors beyond one’s control that can prevent growth as well, so it would be important to consider the context of each individual’s circumstances.