I go do 40-60 minutes on my spin bike 3-4 times a week. I turn on a pandora workout station and keep pace with the songs, raising and lowering resistance to keep my heart rate and breath where I want it....resistance and speed always keeping my legs burning just a little. Most of my time sitting, some standing. A little 5 min warm up and cool down, followed by a 30 min power yoga dvd. This usually gets the job done, I'm happy and covered in sweat by the end.