I struggle with both, and not just as a YouTube roadblock. They're pretty responsible for keeping me single with so little job experience too. Honestly I don't deal with it well still. I'm not sure if one can ever fully "shut it off" vs. learning how to work alongside it. I've been practicing mindfulness a lot (The Illustrated Happiness Trap is my favorite resource for it) and that can ground me in the present well enough to at least start sometimes. I also had a therapist for a while (but I get that's not an option for everyone-it took me years to finally find something low cost).
At best I'll finally get going and enjoy a project I'm working on again. At worst I have these mental breakdowns where I toss up a whole bunch of negative uploads and public journal entries (typically related to how I don't like anything I'm making and aren't happy with my life at 26 years of age). Most of it has root causes beyond YouTube but yeah, I haven't been able to do s**t with my channel for months now but lounge around and not feel motivated to animate. All my uploads have been montages, Vlogs, or really low effort.
Comes in waves, I know I'm looking for that project that I'm really into again. The one for myself. I get really burned about the whole "making this for my audience not me" thing. I just keep on not finding it.
I will say doing live streams has actually helped me though. That and positive comments from fans. Always warms me seeing people actually like me and my content as most of my depression stems from being so alone and friendless.