I usually do HIIT, mostly. I was a runner for years so sometimes I will still go on a long run. ...usually only once a week. Mostly for the theraputic value. I was really addicted to running for years - started when I did cross country in high school. I used to do a ton of milage... but then I decided that I didn't want my body to have that distance runner look. I still run for cardio but I mostly do sprints mixed with a light jog in between sprints. I usually only do about 30 minutes at a time, now. I try to do hills once a week(good for the butt) and I still get in a longer run about once a week ... but mostly for the theraputic value. I like my body much better, now. Like the other women said - Just depends on what your goals are.But don't just do cardio. Weights are important,2.Just my 2cents.