Personally, I never get writers block or artist's blank page syndrome. I feel like I am always tapped into the creative conduit. But where I fail is motivation. I haven't got it. I get excited by a project and then realize how many brush strokes it's gonna take and my heart sinks into my stomache and my hands start shaking.
It's incredibly frustrating. I wish there was a way to fix it.. but I refuse to take medicine. I barely take aspirin for headaches. :/
The only thing that seems to help is creating art in the same room with other artists. Working with a team, or simply next to other artists or even musicians seems to energize me. Which is why I do fine in art school and slump miserably when I live alone.