I tend to give too many reasons for my character’s actions. It clutters up the story and slows plot advancement.
The character is living a life and making normal, every day decisions. We, as characters of our own stories, don’t think about the reasons behind everything we do. We just do the things.
For example, I always mix sour cream with my salsa. It’s something I just do. I don’t even remember the reason I started doing it. I think I just tried it one time because I was putting sour cream and salsa on my chip separately, so, why not mix them together? And it tasted even better! (My wife disagrees).
The point is, characters don’t think about their habits and quarks. They just do them. And giving a whole history of why they do something takes away from the joy of character development for the reader.
One of my characters constantly resets a device to avoid bad memories from when he was younger, but he doesn’t think about those reasons every time he does it. Especially since I’m writing from a first person point of view, it doesn’t make sense to have him think about the history of that action.
That’s what makes interesting character development: showing them do things, but leaving out most of the whys. It’s mystery. Figuring out why characters behave the way they do is part of what keeps people reading.