You cannot teach an old dog new tricks
you can't teach an old dog new tricks
proverb You cannot teach some new skill or behavior to someone who is set in their ways. Good luck getting Grandpa to start going to yoga with you. You can't teach an old dog new tricks.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
You cannot teach an old dog new tricks.
Prov. Someone who is used to doing things a certain way cannot change. (Usually not polite to say about the person you are talking to; you can say it about yourself or about a third person.) I've been away from school for fifteen years; I can't go back to college now. You can't teach an old dog new tricks. Kevin's doctor told him not to eat starchy food anymore, but Kevin still has potatoes with every meal. I guess you can't teach an old dog new tricks.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.