A lot of times when I am completely immersed in my work,  I don't have time to eat and even forget about being hungry.   Recently I saw a piece of news about some scientific research that suggests if we occasionally fast,  we can increase our brain power and even prolong our life span.   I'm not sure if this is really true,  but if we always keep ourselves hungry while seeking knowledge,  then we have the correct attitude and can constantly push ourselves forward.