For me the word is 'ganbaranakya'. It's difficult to transslate because it is so Japanese a feeling. I means something like "we must try hard" or "let's work harder". I think it is a feeling present in the heart of all Japanese people, and something that distinguish them from other cultures. I don't mean that other people don't work hard, but the feeling conveyed by 'ganbaranakya is that life is hard and one must always strive and fight against it rather glide with it or enjoy it.

I believe there is a connection with the sparsity of humour in Japanese society.

How many times a day does a Japanese use the phrase 'ganbatte ne' or 'gambare' or 'ganbaranakya' ? Many times, surely. It's a ubiquitous sentiment, a national obsession with hard work.