Australian actor Hugh Jackman is shown here in The Guardian advocating working hard but not too hard, the idea being that if you work at 85% of your capacity, you will be more relaxed and perform much better. Sports athletes do this. In the French cycling race Tour de France some cyclists practice with much lighter routines to do their best the following day in the actual races. The idea is doing what brings out the best in you. There is also a principle behind this. Intel's founder Andy Grove called it the "slack" principle in which by having slack in your daily routine when something suddenly came up to be done one could accomodate it easily and not waste horrendous amounts of energy tackling the chaotic situation when one tried to do it crossing the 100% of your capacity to do it to reach 101% or 102%. At that point one is not at one's productive best but deteriorating in quality of work. The slack could be 5% leaving an additional slack of 10% for yourself to do things that give your mind a rest which is what sports athletes and productive workers do. In actual practice the work is done in less time with slack because you can concentrate better which means you are getting more done than before this 85% approach. ...