Because then I actually spend time on the interactive/technology side of knitting, and not just fretting over what's still on my needles. I surf Ravelry (way too much), check out other knitters' blogs, and find new and interesting ways to mentally bond with that projects that I'm slowly churning out. I feel a sense of responsibility to keep on chugging.
I'm getting past a mental block, too. I read more and more about certain projects that I or other people may get so excited about knitting, and something goes awry with it, and suddenly, it's unbearable to finish. Unbelievable. I used to think that made me a disappointing knitter. Now I've come to realize that it just makes me more realistic about my projects. For example: months and months and months ago, I started a Lucky Clover sweater. I got lots and lots of it done - one sleeve, back, and one front - and then stopped. I looked at it one day and honestly saw that I was never going to wear it. I had made it out of a cotton yarn that was rather stiff and heavy, and it only drooped when I pinned it together. I still have the pieces that I finished, since I'm just going to wait to frog it until I see a use for the yarn. I have officially discarded it as a WIP though.
Of course, over the weekend, I decided to start a new project. A Central Park Hoodie. Lots of people on Ravelry have knit this one, and I really like it. I just happen to have enough stash worsted in a deep purple color, too. It's a sign.