In Bill Gates' video about malaria and education, he told people that he is "an optimist. Any tough problem, I think it can be solved". This made me think of Professor Randy Pausch's testimony to the members the Congress before he died:
In the testimony, he said
"I don't believe in too hard."
He believed that if enough funding is allocated for pancreatic cancer research, we should be able to raise the survival rate to a much higher one like breast cancer's.
True that there're probably some problems in this world that just cannot be solved. Despite that, I believe everyone should hold an attitude like Gates' and Randy's toward life.
It's this kind of optimism that drives the human civilization forward. It's this kind of belief that took us to the moon. It's this kind of faith that gives us hope so that we believe we can make tomorrow a better day.
Because of this, whenever I encounter a difficult problem, I usually say this to myself
"You think this is tough? There're many tougher problems in this world and some brave people are ruthlessly working on them. Don't be kidding me :P"