Many of my clients come in confused, wanting to know what is their purpose in life. I think sometimes we make the matter more complicated than it needs to be. For the believer it is particularly simple. Micah 6:8 gives a prescription - "The Lord has told us what is right and what he demands: " To do Justly, to love Mercy, and to humbly obey your God".
Now I could go into a long book about the balancing of Mercy and Justice, and how it related to the psychological concepts of boundaries, autonomy, attachment and empathy, but that is for another time. And it would be another book to share what I think "obey your God" means specifically. But the point here is that in the Christian community, for example, "obey God" often is taken as to specifically find out that one magic route He wants for us, and woe! if we stray from that mystical purpose. We then generate a lot of anxiety trying to figure out exactly what He wants. Sometimes it gets to the level of ridiculousness - "Is it your will, Oh God, that I should have the strawberry milkshake or the chocolate milkshake today?"
Now I understand that the Ruach Ha Kodesh (Holy Spirit) has given us the capacity for discernment and we should be sensitive to His voice. But in most situations, even in choosing a vocation or a life partner, there are many choices that are good ones and might be quite in the "center of His will" . In choosing a path, the criteria are simple: Is it legal? (Justice) Is it ethical (Mercy)? Is it moral? (congruent with His precepts, his Torah)? I don't want to debate the exact meaning of these words. I think you get my drift. We don't have to overcomplicate things.
Another helpful perspective on purpose, is the concept in Jewish thought, of "tikkun olam", or "repairing the world". The idea is that the world - for whatever reasons - is less than it should be, and our purpose here is to help in repairing it. Regardless of your religious persuasion, everyone can participate in tikkun olam. I think that people who drift from this purpose end up feeling empty and rely on pleasure rather than purpose to feel good. Asking the question, "Does this add to the repair of the world, or to its destruction?" sometimes brings clarity to our choices. Ignoring this purpose in life, I think, ultimately brings despair. And don't forget to include "yourself" in "the world". Does this choice help my growth and repair process, or aid in my destruction? Does this choice in the relationship bring us closer together in harmony or farther apart in conflict?