To achieve your goals, you have to be willing to put up with a boredom. The monotony of practice is part of the practice.
I know you might not want to hear that. Maybe you want it to be fun the whole time, like it is at the start. But, deep down, you know that it's not going to be like that forever.
And, no matter what it may seem from the outside, even the best aren't motivated all the time. They have the down days when they don't want to do it too. But they do it anyway.
There are two tricks to staving off boredom.
The first is to practice in a way that provides just enough novelty. For example, my workout program changes every six weeks. When it changes, I'm still doing approximately 50% of the same drills, with a few changes to timing and structure. The other 50% is usually a progression on something I've already worked on - so it's similar, but different enough. Yet, every time a new program comes it feels exciting!
The other trick is to make sure you're looking at your progress. Showing up every day, feeling like nothing is changing, AND being bored is very hard work. So. Make sure you're measuring something so you can see progress. Even if it's really slow. Aim to be just a tiny bit better (whatever better means to you) in some way each time you practice. I suggest that six weeks is a good interval to look at your progress. You’ll surprise yourself.
With these two tricks, you can work through the boredom more easily.
But, really, there is no trick. You'll still get bored.
You have to fall in love with boredom.
There's something valuable past the point of boredom.
When you're doing something for a purpose rather than for the novelty value. You can pursue novelty in other areas of your life.
If you get bored along the way, maybe it's a good sign you're on your way.