So we have passed the 25.000 words mark, and we are coming to the end of the middle and the beginning of the end. Or something.
And the middle is always a problem. That’s where the story sags, where the excitement of the start is gone, and the excitement of the finish is yet to come.
I have no figures about this, but I think this is where most people drop their writing and move on to another story, or another job altogether.

I tend to stick to the classic Holly Lisle rule, and I do not write the boring parts. After all, if I am getting bored writing them, there’s not a hope in hell my readers will feel anything but boredom reading them.

So this phase of the writing process is, for me, very fractured.
I write short scenes, 300-500 words long, using a sort of montage technique, condensing the action as much as possible.

1. The characters find a relic floating in what’s left of the external Saturn ring.
2. They debate whether to recover the artifact or let it go and proceed on their main mission.
3. They decide to pick it up.
4. A runaround is set up, a crew is formed. Mixed crew, because the story’s better that way.
5. They go and start the retrieving ops.
6. Something bad happens.
7. The emergency is resolved.
8. The relic is recovered.
9. The adventure continues.

Say 700 words for point – a little more for the lengthy action/suspense sequences – and you get what… 6000 to 8000 words worth of story. And most of it is boring.
It’s “let’s do it!/”no it’s dangerous!”, “I go.”/”You go.”
“Shall we take along Gummo or Zeppo?”
“Hey, what’s that?”
“Where?!”
“We’re never going to make it–“
“We made it, pity for poor old John–“

B O R I N G

And I am doing a writing marathon, so I have no time for boredom. And my readers will have even less.
In the list above, I can compact points 2 and 3 in a short, tense exchange – 300 words in first draft. By now we know most of what we need to know about the characters, so we won’t need to use this dialogue to bring up anything new. It’s just functional, so keep it short.
Drop points 4 and 5 (I mean, it’s obvious they are putting some people on a boat and send them out, right?)
Start at 6 with a bang. Point 6 & 7 are a good, solid 1500/2000 words. Vivid action. Not much talk.
Drop point 8.
Write a line somewhere about poor old John, use his loss as a motivator or complication later on.
Bingo. No more than 2500 words of good story, and a side incident that keeps the middle from sagging.

This, at least, is the theory.
Now a cup of tea, and then on to more writing.