I'm a programmer, a creative person, working on my projects, and regularly I need a short break, so on every break I usually lay in bed and checked the news and I often ended on YouTube watching more videos, wasting hours every day. What eventually helped me was use css to replace entire YouTube (and other doom scrolling websites) with a motivational picture that says:

"One day, you'll realize that your dream died because you chose comfort over effort. Don't let that regret haunt you forever."

And it worked.

The css for yt looks like this:

    body {
     min-height: 100vh;
     background-image:url(https://example.com/effort.jpg);
     background-size: contain;
     background-repeat: no-repeat; 
     background-position: center; 
     background-color: black;
    }
    p,div,h1,span {display:none}

I did the same and it worked very well for me too. Redirect all dumb sites I don't really want to visit with a link to the quote I found inspiring at the time:

"It was a day like this when Marco Polo left for China. What are your plans for today ?"

That's just a first step, your muscle memory to open youtube.com for instant gratification requires time and motivation to go away. But the extra effort of having to disable an extension to fall into patterns you decidedly wanted to end is maybe enough to get you going.

I love this, I block sites during certain times to stop me wasting time but I might add this too.

What, did you edit your hosts file or something?