What are the tips and tricks people are doing to help them maybe extend their sessions or just keep them focused on staying at the tables.

I have usually been doing 1.5 hours for a session..then take a 15 min break then usually another hour... id like to work to that 2-3 hours but find myself getting tired or un-focused at the tables after that hour hour and half ish.
I usually have some chill music playing, bottle of water, Sometimes coffee and some fruit.