I used to use the treadmill at an incline of about 5 or 6, but then I got a Personal Trainer who suggested that I walk for 30 minutes at an incline of 15. (Yes, that is the very highest it will go…). I’ve done this for a couple weeks now and have to say that this part of my workout is the most intensive and gets the sweat pouring off of me more than anything else I do! After my 30 minutes, I put the level back down to 5 for a minute or two, and the funny thing is, that now at that level, it feels like I am walking downhill!!