In writing - novels especially - there are hurdles you have to get over. Things that always trouble you, no matter how much you've written. It can be anywhere, in the beginning, middle or end.
For me personally, it's the 3/4 mark. I'm deep enough into the story that I know exactly where the plot is going, but sometimes it's hard to hash it all out in outlines. Or I'm close to the finish line, but not enough to sprint into the home run. Always, with every novel I write, I get stuck at this point. It's horrible to go from writing so much, to struggling to even write a page. Like running in mud, I just slow down. But this can be good. It gives me time to really consider what's going to happen, and see how exactly everything will play out. Being at the climax of the novel, it's much better to sort out little details here so you don't have to change everything later than go storming ahead with an incomprehensible climax to revise later.
The one thing that keeps me going during this stuck-in-the-mud phase is knowing how close I am to the end. Once I get past the mud, and get to what I call 'the home straight', my finger are flying across the page. I write, and write, and write, because I want to get to that end. If I had any sense, I'd draw out the process so I don't have to go back and fix silly grammar and punctuation mistakes later because I was writing so fast. But I just can't help it. Knowing that I can finally finish the novel I've been working on for long is irresistible. As well as this, the fast paced action usually keeps me writing at a fast pace. The deadlines I set myself help too.
Some people struggle with beginnings. While beginnings do unsettle me first, I quickly get into the pace of the story. But some people find it impossible to write beginnings, and I understand why. You have so many ideas circulating for the novel, but where to start? The one thing that helps with beginnings is knowing that they're not set in stone. When you come back to revise a novel, you might find you've started in the wrong place. In one of my novels, I had to cut out two whole chapters at the start to get to where the story should have started. But that's OK. Once you have a whole draft, it's much easier to go back and see where a story should start, or adapt the beginning you already have. Think of a beginning as temporary, in no way the be-all-end-all of your novel. It's a start, and that's what counts.
Middles can be hard for some people as well. You're far enough into the story that you want to carry on, but the ending is so far away, it seems impossible to ever get there. While there may be action happening, and the plot developing, it's not fast-paced enough to keep you writing, writing, writing. If you find this happening, don’t just struggle through it. If the story isn't interesting enough for you to want to write it, then it's not going to be interesting enough to read. So do something crazy. Throw in a gunman. A murder. An old flame. Anything to stir up some more drama and action, that will keep you motivated to get through the middle and towards the end. You might find it makes the story better in the long run.
Finally, endings can be troublesome. Just how can you wrap everything up in a way that satisfies both yourself and the reader? It's hard to see an end to all that work, even if you know the work isn't really over. First drafts are completely malleable after all. But the writing stage is always something special, to me at least. It's understandable to want to cling on to it for as long as possible. But all good things come to an end, and you have to trust that better things are on the horizon. When looking at the end, things like timelines and outlines really come in handy. You can see the direction of the plot, and this can help you establish just how to end the story. Remember to be true to your characters, and yourself. Don't make an ending fit that isn't right. You'll feel much better if you know you've ended the novel right than if it sits uncomfortably in your plot. Even if it takes that little bit longer to find.
Every person's style is different, and you can find hurdles all throughout your novel. The thing to remember is that when you get past them, you'll be heading towards something great. You will get there in the end. It just takes a little bit of determination, motivation, and work. Actually, a lot of work. But the results are always worth it.