Correct Motivation
The problem with the way most people try and find a suitable career is that they use the wrong motivation. They focus too much on what will make them happy. Consequently, they choose careers based on their personal preferences and personal enjoyment. Their personal enjoyment, however, is bound to change because of their own personal development (e.g., suddenly money is less important, or you realize you're really interested in math) or because they realize that they've encountered something they don't like in their job that they underestimated or overlooked. Since the only thing that ties them to the career is their OWN enjoyment, when the enjoyment fades, the commitment to that career changes, and they're back at step one. The effects of that pattern can be pretty devastating in the long run because (1) you may suffer financially (2) you run risk of feeling interminably lost (3) your chances of building expertise diminish (4) you don't build a strong connection to your job (5) you may end up feeling like you have wasted time (6) it's harder to make your career serve as a source of fulfillment. Obviously this is not the case for everyone, as some people may find enjoyment is job-skipping, but I think most people, myself included, would agree with this premise.
The answer, I think, is to stop thinking about yourself and your preferences and start thinking about it from a different perspective: what is my duty? what is my responsibility to this world? Your duty is something you can think of as handed to you (by your genetics and upbringing or by a deity if you prefer), rather than something that you choose. I don't mean to say that it's handed to you like an envelope that has a specific thing written on it -- no. Rather, you have certain gifts and talents that can be used to better the world. Your task then, is to contemplate (a) what your gifts are and (b) where they can be utilized to produce maximal benefit to mankind. While typology is a good starting point, there is lots more to your personality and abilities that the practice of typology will miss. By discovering your duty to this world, you have a better chance of weathering through job-disappointments, creating a connection with your job, resisting fleeting urges to find something a bit more stimulating (that may disappoint you too), building expertise, and feeling fulfilled.
Practical Steps to Finding Your Life's Purpose and Duty
1. STFU. Your mind is both a friend and foe, but in order to get in touch with your real qualities, you need to shut your mind up. One way to do this is through arousing compassion (reading certain stories, nostalgia) or arousing some sadness (listening to emo music). If you meditate, now's a good time. If you think some is beautiful, be around it, even through the internet. You can also go to the gym and do some intense exercise. Any one of these will work. (1.5 hours)
2. Ask yourself what your best qualities are. What do you do very well? Exceptionally well? What talents do you have? What was your best grade in school? Favorite subject? What have people complimented you for? What was your favorite job thus far? (20 minutes)
3. What types of areas are your skills needed? Where are you, personally, needed? If you had a duty in life, what might it be? What type of career would give you quiet pride? (2 days)