Before trying the 12-3-30 workout, I had been rowing 10,000 meters regularly (which takes about an hour). I didn't want to lose my rowing endurance completely, so I cut my rowing workout in half (5,000 meters), and I'd do that before this walking workout. I found it helped to warm up my lower back, glutes, and hamstrings for the steep 12 percent incline. After getting off the rower, since I was already warmed up, I did a couple of minutes of stretching before getting on the treadmill.
Then I'd hop on the treadmill and warm up a little. I'd walk with no incline at a pace of 2.0 mph for a few minutes, then I'd increase the incline to 12 for a few minutes, and then I'd officially start the 12-3-30 workout.
Even if you're not going to do something like rowing beforehand, it's a good idea to do a full-body warmup before hopping on the treadmill. Then spend a few minutes walking before gradually increasing the incline to 12 percent.
