Me and running in nice sunny warm weather have this thing so far this year.
I head out the door and run and it feels great... amazing... fast.
I check my watch and see I'm going faster than normal (ie anything faster than 6:00/km). After that last attempt at holding on to the pace and getting a faceful of wind for 2kms, I decided that well lets see what happens.
Well a just over a 2 min PR kind of thing happens. Talk about getting some speedwork in.
And now I know what some people mean when they describe running so hard they feel like throwing up.