Actually, as far as I know there is no direct translatable quote, but the meaning in (very rough) essence is... "Enjoy each moment of your travels, they are unique experiences in your lifetime, often never to be repeated again." Literally, it means that for travellers, once they turn around (head home), it's usually for a life time. An exhortation on the fleeting nature of travel and urge to seize the day. Please add a better translation if you have an appropriate quote!