Can you tell me how do you still motivated ?

I think i know what you mean.
We live in strange times to be sure, but we also live in the best of times.
I was a teenager in the eighties. I thought it would be the best thing ever if I could write a book or be a musician or an artist. I was and am a huge sci fi fan, and I tried building my own scratch builds but I knew even then it was a waste of time because computers were going to take over this aspect of film making.
Now I am working on an animated series pilot that i have been working on and off for a decade. I had to wait til the tec and affordability hit a certain level, which it seems to have, in order to actually make it happen.
So we are super lucky we have so many creative options now, however..
At present, despite the thousands of hours I have already put in, no one knows about my awesome story and great characters. I've written almost twenty episodes, but I am the only one that has read them. If I am to finish this I have to maintain enough belief in myself to keep going, and it is hard.
To keep going I have to constantly look for inspiration. A great deal of this comes from the One Piece anime. this anime has been going for twenty years. The characters are in for the long haul. The payoff is still far off in the distance but nothing will stop them. They are willing to die for their dreams.
You and I just need to work hard and be patient.
Dunno how busy you are, but I can always use help. I finally have all the elements and this pilot is going to happen this year, maybe you could help a little for the credit and experience if you want.

One way to stay motivated and not stop is to do two or three things at a time.
Inevitably, whatever you have started comes to a point where the initial impulse stops.
But if you start three different, yet related things, when you get to the point where the first loses momentum, you move on to the second, and when the time comes, to the third, that way, one task helps advance the others, it how to make a braid.
Braiding tasks in this way strengthens and drives them, overcoming moments of weakness.

Set goals for yourself, then strive to achieve those goals.

If the models you have for sale here began making you a lot of money, would that motivate you to create more models? Would success drive you to keep going? If so, consider what it might take to become successful doing what you want to do and then set goals to achieve that. Make it your purpose to reach certain goals on a daily, weekly, or monthly basis. Give yourself small personal victories every so often in the pursuit of the bigger picture. If that makes sense.

Motivation is such a strange animal. For most, it means money, for others, it means getting that new car, new boat, new house, either way, it's still money.

In different stages of your life, what motivates you will change. When I was a teenager it was all about Friday night, When I got married it was keeping my wife happy, and when I had children it was providing for them.

Three years ago I broke my neck and spent a long time lay on my back staring at the ceiling lol. Sure, I could have given up, but where's the fun in that? At that point, my motivation was being able to play with my grandson again and that was powerful enough to get me out of that bed and doing physio as hard as I could.

As Lux said, you need an ultimate goal and that goal will change as time goes on. Your goal can be anything you want it to be in this life, it's the best time to be alive. Sure, we have covid, but we don't have the Black Death, poverty is at its lowest ever, you can eat food from anywhere in the world, you can go to places in hours that would have taken months to get to, and technology is advancing at a rapid rate.

My other tip is to pick a goal that's achievable, and then pick a bunch of others that are just possible. Once you hit the achievable goal then the others will become closer.

Good luck, and never, ever give up!