Studies have found that sitting for prolonged periods of time is bad for one's waistline, blood pressure and cholesterol and some studies have even strongly correlated sitting with reduced life expectancy. But a recent study has found that taking a five minute walk at least once every hour can mitigate some of these ill effects (Thosar et al, 2014)
The average adult attention span is between 10 and 15 minutes (McKeachie , 1999).
Thosar, S. S., Bielko, S. L., Mather, K. J., Johnston, J. D., & Wallace, J. P. (2014). Effect of Prolonged Sitting and Breaks in Sitting Time on Endothelial Function.Medicine and science in sports and exercise.
McKeachie, W. Teaching Tips: Strategies, Research and Theory for College and University Teachers, 10th Edition. New York, Boston: Houghton Mifflin Co, 1999. P69-71.