mend (one's) ways

To start behaving in a different, usually preferable, way. After I got in yet another fight at school, the headmaster told me that I had to mend my ways or else I'd be expelled. No matter how old you are, there is still time to mend your ways.

mend your ways

COMMON If someone mends their ways, they stop behaving badly or illegally and improve their behaviour. He seemed to accept his sentence meekly, promising to work hard in prison and to mend his ways. When asked if he intended to mend his ways, he told us `I'll try my best.'

mend your ˈways

(British English) improve your behaviour, way of living, etc: If Richard doesn’t mend his ways, they’ll throw him out of college.