You're not alone! We're all fatigued by the time we get to the verbal section. That's natural on a test that's so long.
So your goal is to minimize fatigue, not to get rid of it entirely. You will always have some fatigue 2.5+ hours into a test.
Three big things:
(1) Minimize mental energy used earlier in the test: Mental fatigue is cumulative, so the decisions that you are making earlier in the test will impact how much mental energy you still have left when you hit the verbal section. When you're deciding whether to spend time / mental effort on a particular quant or IR question, you have to factor in overall mental fatigue / whether this will tire you out too much by the time you get to verbal.
Here's the most extreme case: let's say that you get to the final quant question and you have 4 minutes left. You can see the question is crazy hard and you know you really have no idea how to do it. But most people will try anyway, thinking that they have nothing to lose, since it's the last question in the section. Why not?
Because you still have verbal to come! That mental energy would be better spent there. So don't waste time on a too-hard math question
even when you think that there's no downside for the math section. (The same is true for IR.)
(2) Minimize mental energy during verbal: You'll also need to make sure that your general processes for the whole test, including verbal, are very systematic / ingrained / a habit. You don't want to have to keep reminding yourself what the steps are for SC or what answer (C) means on Data Sufficiency or what you're supposed to do on CR discrepancy questions. You want to just
know. It's like muscle memory: you just know how to react to certain things. Your basic processes are all complete habits.
(3) Mindfulness: This is a technique that helps you to concentrate and minimize mental fatigue. See here:
https://www.manhattanprep.com/gmat/blog ... mat-score/And some of my students have really liked this (though it's a paid resource, FYI):
http://www.10percenthappier.com/mindful ... he-basics/