While each scene needs internal and external action, so does the overall story. The way to successfully do this is to examine your main character and give them an outer problem and an inner problem at the start of the novel. Like this:
Marin's outer problem- To figure out what to do about the new guy in her life, whom she's fallen in love with, despite feeling like things could never work between them.
Marin's inner problem - To accept that she can't control every aspect of her life.
Your character will see the outer problem. This is the big one they're working to solve throughout the novel. Almost all your scenes will have something to do with the outer problem, either moving your character closer to or further away from solving it.
The inner problem, however, might be something your character doesn't even recognize needs solving. Maybe it isn't even until the last 1/4 of the book that he or she will realize they've got this whole other issue that needs solving. Often they're forced to face it during the "dark moment" of the book, the moment where all feels lost.
But even though your character doesn't realize there's a problem that needs solving, in your crafty writer way, you still need to be nudging him or her towards the solution. Whether it's through comments that other characters make, or just finally giving a name to what it is your character's going through. Like in Marin's case, it might not say anywhere, "Marin has control issues," but we can see it in the way she interacts with her friends, family, etc.
Both problems need to be solved at the end of the novel. Otherwise, why on earth did we just spend our precious time reading those 75,000 words?
Is this making sense? I'm writing this at the end of a long day with two kids, so I don't exactly trust my brain right now. Only half of it is thinking about writing. The other half is thinking about Reese's Pieces.