Many sources I have read state that walking is the best single exercise. I have a treadmill that I use, but not every day. One of my goals is to use it at least 4X/week. On days that I do extensive housecleaning or yard work, I count that as my exercise for the day. I also have several written exercises for specific body parts such as upper body, back, and neck that I want to work into a planned routine this year, maybe while watching TV.