How can I stop my mind to focus on studies/work/meditation

Who asks you to stop the mind???

What is being asked is control its wavering off to thoughts that are not in sync with your action.....

Just like you don't want to lose senses while driving.... by thinking of some fight/argument or even a beautiful memory..... because it can be life threatening, dangerous and harmful.

Similarly when you are doing anything, if your mind is wavering off to something else, they say, "stop losing your focus."

To maintain focus, you cannot stop it. It is that naughty kid who is very arrogant and aggressive, when you try to snatch his favourite toy......the toy for your mind is your thoughts...... so when you will try to force stop them they will pile up one after another.....

So to focus on a job, start breathing deep......

..........Oxygen is mind's favourite chocolate........

Feed it with oxygen, it will forget playing and sit quietly.

And PAY ATTENTION to breathing.

Not just meditation, any job can be accomplished using this technique.