Most writers have no problems giving their characters quests, but what I mean when I say "journey" is the emotional kind. Before I delve deeper, there are exceptions. If you write action and adventure, then the focus is on the action and adventure, not really the character. Stories like Jack Reacher won't have much character development because it's all about the thick plot.

My favorite kinds of stories involve characters who start off one way, then through self-discovery, embrace a better version of themselves by the end of the story. This is their character arc. Sometimes planning a story can follow the character arc, especially in contemporary romance and young adult. Even a lot of action movies try to squeeze in a small character arc. (For example, a stone cold mercenary learns to care about something and fights for a cause.)

If you Google "character arc", you'll find tons of information. My favorite interpretation is this: Each person carries an Identity and an Essence. Identity is how you see yourself, and Essence is who you really are inside. If you are lucky, they are the same thing. But most of us aren't that lucky, and therein lies the conflict.

A few examples: Greg is pretty smart, but his parents called him a loser all his life, so he thinks he's a loser. Marsha thinks her life is perfect, but deep down she's growing more and more disgruntled at work. Chris's self-doubt and anxiety prevents him from embracing his full potential as a talented writer.

You may have seen various ways to structure a story plot. Most of them involve three primary "acts". In a character arc, they perform the following roles:

Introduce protagonist(s) and create empathy. They start out fully in their Identity, but throughout this Act, they'll face an opportunity and the reader will glimpse their Essence.

The character wavers between their Identity and their Essence.

Character fully returns to their Essence, faces the climax, and lives their life transformed.

The explanation of the three acts were borrowed from Jami Gold's "Six-Stage Plot Structure Beat Sheet". (I've added an external link to the page.) There are tons of different beat sheets you can use to plan out your story. The trick is to find one that suits your style. This one suited me more than most, although I still have lots of trouble filling it out before actually writing.

By planning your plot around the character's emotional journey, your story has direction. And when you have direction, you are less likely to meander or encounter the dreaded writer's block. It takes practice to master the beat sheet. I still haven't mastered it myself, so give yourself time to get your brain used to being structured a bit. I love writing by the seat of my pants, but discovering the character arc has helped me tremendously because I am less often lost.