On my easy days, I end up running too fast. How do I stop overdoing it?

For training, easy runs should make up the majority of the workouts. 

Many runners think that if they go faster, they’ll get faster times, but that’s not the case. 

Easy days prep the body to endure longer distances, like a half or full marathon, and increase cellular efficiency needed to metabolize fat for fuel. 

These happen because of the time spent running, not speed. To pull back, set a total time target and don’t obsess over distance or splits.