I checked out the fitness room at my new place today and reacquainted myself with the elliptical machine. Yawn. What a boring device (no offense to those who use them because they are not able to run). My feet go numb because they are stationary. I gave it thirty minutes of my time and then switched over to the treadmill. I put my speed on 5 mph and concentrated on what was outside the window, namely a red fire extinguisher. I like it when my mind empties and can have singular focus on one thing. I was in the zone and I could have stayed in the zone for another twenty minutes, but I can't exercise all day long so I limited myself to 45 minutes today.
The benefit of the treadmill is to be able to fixate on one thing while running. My mind tends to wander a bit and creates "roadblocks" when I'm running out on the asphalt or trail. The red fire extinguisher allowed me to focus all my attention to it and not pay attention to the time or distance on the treadmill.
The negative aspect of the treadmill is that the surface is not super comfortable. Sure, I run on trails that have pointy pebbles on them and that's not always comfy, but it's different. Earth gives under your feet. Plastic does not.
I guess I'll have to weigh the pros and cons tomorrow when my body tells me whether or not it liked running on the treadmill. Time will tell.