Born to Run

I started running. I'm running a solid 4km once a week in a little over 20 minutes. Pretty hard to push myself but I want to go 6km soon. I have to train my body though. I barely finished 4 before ... but now I can clear it fairly well. I want to do the same thing but with 6km .... I just have to change my route. I feel as though I shouldn't finish my route every time. I feel as though it's mostly mental.

Anywho, here's a book about running that apparently a friend told me about:

http://www.amazon.co.uk/Born-Run-Ultra-running-Super-athlete-Tribe/dp/1861978235