I draw when I'm -
1. Stressed
2. Bored
3. Down
4. Happy
5. Pensive
Drawing gets me out of those moods (Except the #4).
And the moment I'm out of those moods, I can't seem to continue drawing the same picture because how I feel and what I see becomes completely different.
Here are a few of my incomplete drawings.. you'll totally get what I mean.

At the moment, it's a disembodied head.

I think I unconsciously copied the cat from somewhere. I may have changed a few things but the form looks TOO familiar to me to be my own. I'm sorry.
This is probably about 50%.

TRY TO GUESS WHAT I WAS LOOKING AT WHEN I DREW THIS?!
It was supposed to be a mouse, mind you but became a rabbit.

I forgot to draw shoes.

I looked at my work, said "SCREW THIS SHIT" and drew this.
The bottom half is still under construction and has been for the past 5 months.
No shoes.
Yes, I like drawing girls.