I have this massively.
I suspect ADD. Trouble organizing/planning/sticking to things. My room is also a reflection of my mental state, it's perpetually a junkyard.
It's like I can't make clear outlines for myself because I get distracted too easily or simply forget about goals. Even when I've written down a goal the next day I've practically forgotten about it or I simply put it ahead of me again.
Same with exercise. I now try to stick to a routine of jogging and healthy eating again, but I have massive trouble sticking to it. I do want to become healthy and fit though. The motivation is there.
I have a job, in which I get things done. I work at night, so no bosses around and I just stick to a list of tasks. I wish I could somehow transfer that to my daily life. Maybe it's because there's a certain pressure at work, because you simply -have- to do your tasks or you get fired. Also sometimes, you just have to stop thinking and start doing.