Tā niánqīng shí zài mǎtou mài lìqi, yǎnghuo le yìjiārén.
When he was young he did manual labor at the docks and supported the whole family.
Tips
usage
Two related senses: (1) literal - to earn a living by selling physical labor (often dock workers, porters, construction workers); (2) figurative - to work very hard at something, give your all. Context disambiguates. The 气 here is neutral tone (qi).
register
Colloquial. Compare with the more neutral 卖力 (màilì, 'to exert oneself') - 卖力气 with the extra 气 sounds chattier and is the spoken-language form.
