Good blog post from Bruce Schneier on learning the ropes in security:
Schneier on Security: So You Want to Be a Security Expert
The key part is: "Computer security is fundamentally a practitioner's art, and that requires practice."
No truer words in security I am afraid. I have found more than any other job I have had, that InfoSec is work you HAVE to take home with you. Sure I kick back and relax, but often times, I have the itch to go read up on new exploits, test them out on my own time. I find that if you don't, you will quickly be left behind.