I'm running the London Marathon again this year and have typically been a 'drag myself round by the skin of my teeth' type of runner. But I've just finished my first session with Gray Caws at the Chi Running Club, and I get the feeling that this is going to change everything!
I honestly can't believe how much of a difference a few tweaks to posture and alignment can make. It also doesn't hurt that the group size is quite small so you get lots of one-to-one feedback.
I'll certainly be going back next week, but thought I'd sing his praises on here as there are probably others out there who could benefit from improved running technique. Apparently running long distances doesn't HAVE to be painful! 
You can find details for the long Sunday runs and workshops on the RW events listings, or for the Monday and Wednesday evening sessions on the site below.
http://www.n8pt.com/?ID=50