A few months back I took off from Fairoaks and, during the roll thought "This is a bit tardy today". Anyway, I faffed with the aircraft a little and finally found that I still had the brakes on (I am now 600m along a 800m runway). Anyway, I eventually got airborne and congratulated myself for, yet again, being a Sky God. It wasn't until a few minutes later when I realised what a numpty I had been in:
a. Leaving the brakes on.
b. Not aborting at the first indication of a problem.