"Fake it until you make it" probably isn't a cure, but there are huge benefits. When I look back at the way I spent the past day, month, or year, I'd much rather have something to show for it. I feel better about myself when I see that I actually did something vs. when I spent the week binge watching Breaking Bad or whatever. When I spend the week doing nothing but surfing the internet, I feel even worse.
I also find that I get stuck in a rut where I don't feel like leaving the house or getting dressed or doing much of anything. If I 'force' myself to do something I don't feel like doing, it does help break me out of that rut. It's just really hard to do sometimes