How I deal with being stuck
Being stuck is a byproduct of thinking too big. Every time I get stuck, I've found a few simple things beneficial for getting unstuck. They are not a panacea but always help me move the ball forward. I've found these strategies mirrored in many conversations I listen to and books I read. Whenever I have trouble making progress, I remind myself of these as quickly as possible.
The biggest problem I find myself having is looking too far ahead. I've found it when buying a house, heard about it for writing a book, and experience it regularly while developing software. It is so easy to focus on how it needs to end up and everything that needs to happen in between that it can be hard to start. It's critical to think deeply about it. Imagine building a house and not planning where the plumbing would go. You would have a nightmare trying to get the water to and from the right places. But you're overthinking if you're not pouring the foundation because you're concerned about where to plant the trees.
Listening to Rick Rubin on The Huberman Lab, I loved two pieces of advice he gave on writing a book. He says to think of it like writing a diary. You're the only audience. Don't worry about perfection. Just get it down. Then he says to complete it. Not to complete it perfectly, but to complete it as rough and crappy as possible. The focus needs to be on finishing it rather than finishing it perfectly.

There is a throughline in his advice, and that is imperfection. I'm a perfectionist, so embracing that is hard to deal with, but I find myself the most successful when I can keep imperfection as my north star—always expecting some unknowns to be out there still, some doubts about what may not work or could go wrong. You discover so many more things you never would have in days of thought and planning by getting a crappy version done.
After it's finished, you can take everything you've learned and discovered and sand down the rough edges. You can remember the commonalities and optimize or remove things. You will recognize things you would've never seen without reaching the end, no matter how much time you spent trying to plan. It may seem counterintuitive, but you will have a better final product more quickly if you spend more time fixing a rough draft than making a perfect first draft.

But how do you start? That's always the most challenging part. I love the book Atomic Habits by James Clear because it makes anything seem achievable. If you want to read more, don't set a goal of reading 50 books this year. You will find you've read none at the end of the year because 50 seems like such a huge mountain to climb. Instead, set a goal of reading one page every day. That is how you build a habit. That is how you get something done. You find the smallest, most achievable piece of where you want to end up. Something so small it would seem silly that you couldn't do that.
Seneca said, "The fool, with all his other faults, has this also—he is always getting ready to live." They're always planning to do something. They're always thinking of starting something. They're trying to figure out how to solve a problem. That is the same stuckness. If it seems too big or the endpoint is unclear, no matter what it is, finding the first step, something that you can do quickly, will get the ball rolling. If you were to have 1 hour to make progress, what would you do? If you had 30 minutes to make progress, what would you do?
Once you take that first step, you'll find momentum. The next step will become more apparent. The one after that will come into focus. Before you know it, you will be flying along, getting done faster than expected.

Nothing is foolproof. Sometimes, you find yourself unable to come up with that first step. You can't see the picture. That's when it's time to step away. Go for a walk. Work on something else for a while. It will be percolating in the back of your mind. The number of times I've had an epiphany about something I had been stuck on for days or weeks during a run is too large to keep track of. Even if your focus is elsewhere, your mind always works on it.
That is also why you should do everything possible to start. Until you start, it will always be there, distracting you. You may not think it's doing much damage, but it will bubble up in your mind, taking attention away from what you're working on. Those moments of distraction add up to hours where you're not doing your best work. One of the best pieces of advice I've heard on achieving something big was from Tim Ferriss. His rule is "two crappy pages per day." Even if you're not feeling it, make some progress, no matter how insignificant or poorly done.

The only way to build momentum is to start. The only way to do something big is to make some daily progress. I always remind myself to break it down into manageable parts, find a way to make progress and get something, anything at all, done. There is always time to improve your work, but that's impossible if you never start.
Get started on that thing you've been dreaming of doing. Take that first step.