APAD:You can’t teach an old dog new tricks

‘You can’t teach an old dog new tricks’ means that it is very difficult, if not impossible, to change the way a person does something when they have been doing it the same way for many years.

In other words, you can’t change someone’s long-established ways, especially as people grow older. The expression can relate to a person’s habits, traits or mindset.

The "old" might not be exactly old (age), but stubbornness.

 So reserve a puppy mentality  at all times one will be young 4ever.