*blinks*
The logistics here are confusing me.
If you'd been driving a car, got on the M25 for the first time while driving and shagging for over 100 miles I'd be well impressed and would offer to buy you a congratulatory beer... and wouldn't be at all surprised about your aching back.
On the other hand... If you'd just hit the M25 for the first time and did a paltry 'over 100 miles' and your back hurt, I'd call you a wuss and be done with you. (unless you have back problems normally)
You probably won't care which way this goes but I felt the need to clarify...