Question: I'm 1/4 through my first novel, with a pretty solid 12 page outline of the whole thing. After years of reading books about story structure, I think I have a good grasp on how to make a plot work.

My characters, however, are turning out to be quite flat, uninteresting and generic. They do have motivations and I'm putting a lot of effort into making sure they act accordingly, in a logical way according to their goals and the story seen from their perspective, etc. But they don't feel "alive".

I've read about the archetypes in The Writer's Journey, but that's about it. How can I make my characters come to life?

Answer: 
Your problem may stem from the fact that you are writing a book too much "by the book." Characters aren't like bits of code. Unless they walk around in your subconscious, speaking and breathing and acting like real people, they won't seem like real people on the page. If your characters don't surprise you, they won't surprise anyone else. Novels are about people, not structures, and as a novelist your job is to find a structure that fits the people in your story, not the other way around.
I think one of the problems with character development in novels is the author's liberty to spend periods of time explaining a character's motivation to a reader without the character actually having to say or do anything. A chapter that has the ostensible position in time and space of someone sitting in a chair, reflecting on a dramatic problem, is something that crops up from time to time. That reflective period can info dump a whole heap of incidents in summary and leave the character in a position where the next things they say and do are obvious to everyone.

The problem with that is that doing this is dry and it restricts the things that you need to have the character do in order to establish character through action. It also means that you miss opportunities to flesh out character through interaction and action.

There is nothing wrong with having a character make a seemingly bizarre action that they later have to explain, possibly to another character. Also it is possible that characters don't always agree with each other's motivations. These nuances of character are what flesh out the interactions and make each character grow and deepen.

I lucked into character development boot camp, I did a film-making course where I wrote a lot of scripts. They weren't great scripts but they taught me the nuts and bolts of what do when you can't just gear-shift into "exposition mode" and have a slow beat of characters reflecting on their own pasts.

If a story can get by with out that kind of thing it will be richer for it. It is a path that should only be taken when absolutely necessary. Always explain exactly as little to the reader as you need to in the moment to keep them reading the next few paragraphs. Info dumping is the gentle story killer, smothering under the guise of explaining.