Writer's Block

After over 1200 blog posts, I sometimes have a difficult time determining what to write. I can only assume that professional writers feel this problem regularly.

There are times where I get a writer's high (taking it from a runner's high) and have urge to write a novel full of grammatical mistakes. These spurts seem to only come when I'm busy doing other things. It is quite unfortunate since I usually lose the motivation to write once I have time or even more commonly, I don't remember the ideas I intended to write (I don't even get a chance to leave myself a note).

Any tips from any of my readers?