A research in Massachusetts Institute of Technology is trying to demonstrate that a human has naturall lifespan of 100-120 years but the misfunction of cells by some stresses shortens the lifespan. It's proved that more than 80% of diseases except infections have something to do with stresses. So stress has come to be recognized as the awful enemy and the threatening of human life. However, on the contrary, it is often said that it's dangerous for one to escape and be free from stresses perfectly, so it's the most necessary for one to be used to moderate stresses. That result in immunization aginst stresses and in sturdiness. I think that it in other words means that if one has vigor, courage and joviality he or she can live without yielding to stress. Vigor is gumption and robustness. Courage is the motivation of coping with things positively. And joviality is the feeling of fun and joy. I think that the three are so ideal as the human attitude toward working. One dies as soon as he or she comes not to move. On the other hand, one yields to stress and catches disease as soon as he or she works harder than possible. Nowadays the common sense of that working is more effective health than anything else is well-known. But there have not yet exist the common sence of how one should work. I think that human beings are gifted by nature with vigor, courage and joviality but we have forgotten the important things.

Many people have thought that one's lifetime is intrinsicly fixed. However, recently it turned out that one's lifetime depends on his or her attitudes to living.