I run about 3 times a week (I know, should be more - but there's drinking to be done...). When I run outside, it's usually about 3 miles at a light jog. Inside on the treadmill, I don't go for distance - just time. I'm a huge believer in sprinting/HIT. I do cycles of 1 min at 6 mph, 2 min at 7 mph, and 1 min at 8 mph, then 2 min to cool down and repeat.