When respondents say the reason they don't exercise is time, I'm not sure that's necessarily true. I think what they really mean is that their lives are so busy it is too difficult to use that 30 minutes of time you have towards exercise. Suggesting doing intervals is counterproductive. Intervals are painful. If they don't hurt then its not an interval workout. This is what scares people from doing these everyday. Its hard to get out of a warm bed so you can feel pain. Its sucks coming home from work and feeling pain. That's why we should be encouraging lower intensity workouts everyday (instead of hard workouts twice a week). Your mind can relax, and you get a tremendous health benefit from even just 30 minutes of light exercise everyday. If you do it everyday it becomes a habit, part of your lifestyle.