Yes! When I'm depressed I can't move too. I mostly depend on that mood. I do agree with him though, but for me, being productive is acknowledging that depression and using that to be able to create a strong piece of art.. which somehow drives it away because you got that feeling of satisfaction after being productive.

I have read in a research that creatives are more likely to be depressed because they are highly sensitive ones.. they see experiences in a different perspective.