After finishing my recent cross country race I was feeling pretty burned out so I took it easy for a couple of weeks to unwind. When I started running again I felt like I needed to change something, but couldn't put my finger on it. I went out for an easy run and found after a few minutes that my Garmin was still measuring kilometers instead of miles, and realized this was exactly the kind of change I needed.
I've always measured my runs in miles; I don't know why, I guess because that's the system of measurement we use for everything else. But races are usually measured in kilometers, and my workouts have been increasingly focused on my races, so the metric system seems like a more natural fit.
Another nice thing about the change is that runs seem to go faster when my watch is chirping the splits each kilometer instead of each mile; it breaks the workouts into small increments, and you get more frequent feedback on pace. So for now I'm enjoying the fresh perspective.