表達 “swim upstream 向上游” 原本指鮭魚這種幼期在河裡生活的魚類到了秋天就會逆流游到砂礫遍布的上游河床產卵的習性。要完成這段游途很不容易，而且會消耗巨大的體力，但正因如此，鮭魚才得以繁衍生息。
在日常對話中，“swim upstream” 比喻 “一個人本可以輕鬆簡單地做某事，卻選擇了更加艱難的道路”。其中，“upstream” 是副詞，意思是 “向河、溪上游地”，它的反義詞是“downstream 向河、溪下游地”。
She was very happy to retire. She felt like she had been swimming upstream for years, commuting over two hours morning and evening to do a stressful, badly paid job she did not enjoy.
Few musicians have the courage to swim upstream nowadays – most prefer to follow trends and make music that is popular but not innovative.
Although in the beginning it felt like he was swimming upstream, he persevered and managed to convince the shareholders to drop their resistance to his plans for restructuring the company.