How to stay focused on a game?

I have been struggling with this issue, I play good almost the entire game but suddenly I make a mistake especially in OTB tournaments. I don't know how to overcome this issue. I can understand that I sometimes loose focus on games online cause of the notifs and I don't really care about that but if this happens in OTB it is a problem. Most of the games I lost in OTB is cause of this or else I think I can play very well. Once I was in a equal position vs a 1800 FIDE and then I it was my move, I could not concentrate and played my move without much calculation which made me lose the game. Can someone help me out with this

What’s OTB?

Over The board

Chess vision

Train your brain muscles

Tactics motifs mental endurance

Most beautiful wonderful & yet important is chess patterns recognition

Pawn structures

Do some physical activities, excersses, drink more water during the OTB chess games, don't wait till you feel thirsty...

Ur last meal should be before OTB tour. By at least 5 hours, should be full of carb.

Catecholamine, Astylecoline ,

أشباه الموصلات العصبية الهامة لجسمك

The kind of food you eat, stay away from fat specially before tournament of OTB cuz it takes a lot of time to get digested & the results are ketones

Vitamin B12

Most important are:- ur chess vision must be sharp via pattern recognition & pawn play, it'll save a lot of time calculating

thank you for your suggestions

Download a decent biorythm APK from Google store

It'll help you knowing more about your mental status, duration, why you are out of concretion...

Find out what is pomodoro technic

You Always Welcome

Try to join this club, there're a lot of chess materials in Studying time forum...

https://www.chess.com/club/group-c947ab355a9a785ca4e1871319f57960

I tried to invite you but u don't accept invitations

I also have that problem