When did this happen?

When did I get to the point where I can run 8.5 miles (and follow it up with 15 the next morning) and not want to lay in bed and sleep for the rest of the day? And it's not like all I did yesterday is wake up and run. I had work, came home, made dinner for Dave (and me when I got home) then went running and after that I had all the energy in the world?! Friends came over, we played cards, it was a crazy Friday night! So, my run wasn't an LSD run either, it was 50min tempo, so under 8:00 pace. Then I had long-ish, easy 15 miles this morning. What?! I don't get it, I guess I'm turning into a bit of a runner???, which is still weird to me because less than 2 years ago I'd never run more than 3 miles...a little over 3 months until marathon #2, stay tuned....