It is always advisable to spend some time studying half an hour or an hour before starting to play, review the most interesting hands that you have played in the previous session, try to spot errors and correct them, for this we have programs such as the Holdem Manager or the Poker tracker .
Reviewing concepts and correcting mistakes can help you avoid making them again for the next few hours and will reinforce what you have already learned so that you can focus on improving your game.
Set game times for yourself and schedule your session including breaks.
In the case of playing cash games , it is very simple since at any time you can close the tables and take a break that you can take advantage of to take a walk, have a drink or eat something.
When you play poker tournaments it is somewhat more difficult, if you are an experienced player you can calculate the time that a tournament can last according to the structure and registered participants.
The most recommended thing is that you take advantage of the 5-minute breaks offered by online poker tournaments , or in case you have been eliminated earlier than planned, take advantage of that free time that you have until the next one on your agenda.