So what does make your characters tick? How has their character been shaped? By upbringing alone or what they learn (and also what they learn from direct experience). What happens to those characters who cannot seem to learn from their mistakes?
How do some characters influence others (for good or evil)? Can your characters "break their programming"? There are also good stories to be read and written about characters whose motivations change during the course of those tales. (A Christmas Carol , one of my favourite works by Dickens, is a classic example of this. Another is Jane Austen's Pride and Prejudice.).
And then there are stories where the motivation makes sense to the character but not to anyone else in that story. Countless horror stories (and crime tales) have come and can continue to come from this starting point.
It can be helpful to list motivations and test whether they really are strong enough in your character. My Eileen is motivated by an overwhelming urge to ensure justice and fair place. Her blunt honesty is a result of this and of course lands her right in it but it is all true to her character. So I would list here "justice", "what does her love of justice lead to?" (confrontation with the authorities for one thing!) and so on.
Stories in all formats make the most sense to me and are the most enjoyable when I can see what the character motivations are. I may not agree with them (especially in the case of villains) but I can see where that character is coming from - and then I am generally hooked on the story to see how it pans out, which is precisely what the writer wants to achieve.