Did you know the best paid are about twice as likely to work long hours as the most poorly paid in a company? And most often it's because of the former's willingness to work long hours. This often leads to employees burning out at some point.
Then, how does one be more productive while not working themselves into a stupor? This Harvard Business Review article suggests, among other things, to set a metric and track the changes accordingly. To read more, click on the link.