老当益壮
old but vigorous; all the more aspiring in old age; be inspire despite old age
～，宁移白首之心；穷且益坚，不坠青云之志。(王勃 《滕王阁序》)Age should make one stronger,and it should by no means change the mind of the white-haired;The more difficult the circumstances,the firmer the will(or the more determined and aspiring).(Preface to the Poem on Pavilion of Prince Teng by Wang Bo)
老当益壮lǎo dànɡ yì zhuànɡ
当：应该；益：更加；壮：雄壮。原指年纪大了，志气应该更壮。现多指人虽老了，但干劲更大。old but vigorous, have a green old age, old in age but young in spirit, gain vigour with age, more vigorous with age