i run outside. i used to run on a treadmill some years ago as I figured I could just run till I wanted to stop the get in the car and go home but now if I run on a treadmill I don't really feel like I'm running. more just trying to not fall over
don't get me wrong. if you prefer running on a treadmill that is awesome. i know you can set inclines and stuff and get a super work out from it but it's not for me.
i would like to hear others opinions