Internal conflict without external conflict

I have developed characters, their personalities, motivations, flaws, wants, needs - I know exactly what their internal conflict should be.

The problem is, that I don't know what to do with the external conflict. It could be anything that would fit their inner struggle and growth, which basically works in both a normal and a fantasy setting. The main character would still try to find her purpose, the impact character would be looking for his inner peace, with the overreaching theme being self-worth etc - no matter if they were dimension travelers or university students.

Is an internal conflict enough for a whole plot? Do I need a concrete antagonistic force or is it enough if the character flaws are the worst enemies (man vs self)? Or does every internal conflict need a mirroring symbolic external conflict with tangible goals?

Answer: Usually it is the external problem that forces the internal conflict.

For example, let's say you have a character full of self-doubt. That situation could exist for years with no change. But if they are suddenly put in a position where they are pressured to believe in themselves and act accordingly, because that looks like the only way they can deal with the external problem, then they have to resolve that internal conflict one way or the other -- either choose to believe in themselves or realize their self-doubt is justified (and perhaps the right tool to deal with the problem).

So think about what kind of situation would force your main character to discover a sense of purpose. What would lead your impact character to find or abandon inner peace? What would put them in a situation where they have to face up to their inner demons or answer the call of their inner angels?

To put it another way, an external opportunity or threat answers the question, "Why now?" Why is this the time for the character to resolve their inner conflict?

Ideally, the choice the main character makes, how they resolve their inner conflict, should be what determine the outcome of the story, whether the external problem is solved or not.

Now, there are stories in which the external problem is on the back burner, and most of the page space is devoted to the main character's inner arc or the relationship throughline. Sometimes the external problem is just a catalyst to get the other arcs moving. But even then, having the external problem adds a degree of narrative drive that engages the readers more effectively.

Without an external problem, a story can feel like it is not really about anything.

Best of luck.