Easy run - 30 minutes on the treadmill

The Legendary John Ferguson's training plan called for a 4 to 5 mile easy run. Because I was running on the treadmill, I just selected a 36 minute run -- assuming an "easy pace" for me would be about 8:30 per mile. 4 miles at that pace is 36 minutes. I'm getting better settling in on the treadmill!