Mind is the biggest prison, if u just caught your self there is no escape
They say ,

MIND IS BEAUTIFUL SERVANT BUT THE WORST MASTER

And there is no escape if the prisoner is your very own servant, this prisoner will avenge you till your last breathe

Avenge you for all those bad things you have given him to think about, all those things which weren’t necessary to be given a thought about

Now, now to avenge you he’ll put you in a small box of memories, which will have both the good and the bad one’s
The bad one’s will make you laugh till hours, and the good once will haunt you till the dawn. And before you even know it you are locked up, and u don’t even have the key to your very own mind, so know now you are in a box of traumas hitting you from left right, up down

But now think of a time your mind was a peaceful servant you gave him, junk to eat, trauma to absorb and bad things to think about
Then what is the use of a mind which is not even under your control, that is why budha says  Don’t try to win all the battles outside  just win one battle inside.
So now you understand why is it important to give your mind the nutritious food but not the junk. You give him good things to think about you will never be locked up

~REET KAUR