I doubt that this restlessness is limited to INFJs, though it does seem to be fairly widespread in our type. I have felt this way for much of my life, and, if I were to be completely honest with myself, still feel it to a large degree, somewhere deep down.
I spent my late teens and most of my twenties working simple, manual labor jobs, saving money, and going on extended backpacking trips. Always at the back of my mind was the thought that I should be working toward something, should be putting together some sort of life plan, or saving the world, or composing some great work of fiction, etc. I simply could not motivate myself to follow one particular path. The only certainty lay in my desire to travel. After many yeas of this "aimless" wandering, I finally gave in a the age of 28 and decided to join the military as a linguist. I thought that this would be an excellent way yo force myself to do something. I knew that I would not be able to escape; that I would have to follow through and actually do something. I worked very hard and did become an accomplished Arabic linguist, maxing out the test scores. Alas, even this was not ultimately enough, and I recently left the military.
Selfishness gets a bad rap. Every one, every living organism is selfish. Everything competes for resources (even plants). Everything moves towards its betterment, not its detriment. We always do what pleases most or harms least. And this is natural and good. You help others because it makes you feel good to do so. If it makes you feel bad to help someone, why do it? Even so-called noble or generous acts are borne of self-interest. I think it is best to move with this selfishness, to find something that brings you pleasure, and which simultaneously benefits others, and wallow in it (to paraphrase Robert Heinlein). If you are self-fulfilled and content in and of yourself, I do not think you can help but benefit others. On the other hand, if you are lost and aimless, unhappy and confused to the point of inaction, you help no one, not even yourself.
I think much of this restlessness and dissatisfaction depends upon where one sets the bar for success or merit, as well as how we define individual purpose. How much of this drive is internal, how much external? How much are we influenced by society's view of what our purpose should be, and how that purpose should be pursed and accomplished, and how much is purely a result of our own impulses ad natural inclinations? I think that we often have these grand visions, these grandiose notions of what is meaningful, so grand, in fact, that it is not realistic. Such that, rather than accomplish some small, meaningful "good", we do nothing whatsoever, when a smaller, more realistic goal would have at least afforded us a small measure of peace. Ultimately, nothing "needs" to be done, and we forge our own purpose in the world, and there are no incorrect purposes.
Have you ever read Of Human Bondage by W. Somerset Maugham?
