what I should've told the procrastination leader

My problem with motivation is really that every time I think about my research, or even glance in its direction (literally or metaphorically), this voice in my head starts chanting "I can't do this, I can't do this, I can't do this" and doesn't shut up until I find a blog or something to distract it with.
The times when I do force myself to do something work-related anyway, it's a struggle because I'm fighting against this current of self-doubt (which is actually pretty certain) on top of trying to do the task. I can avoid waking up the voice by sneaking around to do things that don't directly contribute to my project, like finding articles (but not reading them) or starting experiments (but not finishing them or analysing the results). That's how I've made it this far without getting kicked out of grad school, I think, since my project was well-defined enough that I could do things without actually having to think about them, up until recently, but now I'm stuck.
Supposedly, I could just tell the voice to shut up, but I don't think I'd be very convincing, since I think it's right...

Except, if I really believed it, I would have to drop out and find something else to do. When I'm not faced with work, though, I think that I could do it, if I just put some time and effort into it. I don't know how to keep that little flicker of confidence alive in the face of that gloomy voice.