What is it with pace? (Running)

froeschli

So I try and do a fast 5k, manage 33mins and change. Then, 2 days later, I go on my longest run yet, and in doing so beat my 5k time by a minute, run my fastest ever 8k and finish 13k with an average of 6:38 min/km whereas before it was always around 6:50. My pace actually kept getting faster the longer I ran.
Yes, it was a different route, straighter (as in not curvy) but hillier, and parts I ran on the gravel shoulder of the road or in the grass. Temperature etc were the same...
I didn't even try.
That just puzzles me.

Anyhow, I think I'll just quit trying to go fast

And nope, no real question here...