Let’s look at two pace-killers; A character bogging down in his/her own head, and just two people talking.

It’s so tempting to get inside the head of your beleaguered character to let us hear what she’s thinking, but therein is the problem: That’s telling, not showing. Consider:
“Tara desperately wanted his masculine arms around her, encompassing her, but what about her fiancé? What would people think? But I want him, I need him, he makes me feel…”
Yuck on two levels:
- Telling us isn’t visceral; we don’t feel what Tara is telling us she feels.
- People don’t think like that. We only form thought into words when we are formulating thought to tell someone, or when we are constructing an argument (in essence, what we might write down if we were so inclined). Rather, we feel, we imagine. So, to the reader, it doesn’t feel real.
So much better to show Tara’s inner turmoil through her interactions with her fiancé, and whoever “he” is. Does she start arguments? Stay away from her fiancé? Shudder at his touch? All of these are infinitely more interesting than being told what she feels. It also forces action, since there must be two or more people in the scene, and conflict because she herself is conflicted.
Stay out of your character’s heads as much as possible and play out scenes that show us the anguish.
When you do, though, beware the talking heads.
In playwrighting, talking heads refers to scenes where people are just… talking. How boring. Worse when they’re talking about their feelings. Think about the Avengers scene, when Steve and Tony are talking… while they split wood. They take their frustrations out on the logs, culminating with Steve ripping apart a giant log with his bare hands. Best scene in the movie. Of two guys talking. Followed by Tony and Nick Fury just talking while repairing a tractor.
Non-examples are in Star Trek Discovery (if you have seen the last episode but plan to **SPOILER ALERT*** don’t read any further (for my personal opinion of Star Trek Discovery, and more spoilers, see here).
Hundreds if not thousands of drones are ripping apart starships, whittling down shields, and like so many times before, Michael and Spock are just standing there talking… for a long time… about their feelings! Every second they dither, people are dying, ships are exploding but they keep talking. Now, if something weren’t working and they were talking while fixing it, working their frustration and feelings into the task at hand, I wouldn’t have been yelling at the screen so much (something I do regularly).
This is a particular problem in visual media, but it informs prose, as well. Great dialog that is fast and clever can cover inaction but still, add the element of action to show us what they’re feeling! Go through your story and find scenes of talking heads and lengthy inner monolog and set them in action!