I ran the fartlek workout last week Sara. (Sort of - did it as a ladder.) I wanted 6-7 miles, so I ran a mile w/u, then 3:00/1:30 x 5, 2:00/1:00 x 4, and 1:00/:30 x 3, then a 1 mile c/d. The "on" was at 5K pace. OMG. It was exhausting. Great, but exhausting! Not sure what that says about me as a runner, but it felt like a great workout. Thanks!