Treadmill on Three, One Mile

This is second day I walked on treadmill, speed 3 for 20 mins., 1 mile. I use to take a nap every morning, but since I started walking on treadmill I feel better and have more energy. Before we went on vacation I was walking on speed 2, tried speed 3 and now 2 is too slow for me. I use 2 for cool down.