Lol......that's a tough one, and something natives rarely if ever think about... I'll be honest, i'm struggling to come up with a logical answer. If I had to give a reply, I would say it perhaps has to do with specificity. "The" pressure is for a specific pressure, not just any pressure... For example, you as a person my have no problem stepping up to the plate and hitting a home run for the baseball team. In this case, it's still pressure, but that pressure doesn't bother you. However, if I ask you to speak in front of 150 people, perhaps that is not pressure you do well with....and when "the" pressure is on, you fall short..... Again, specific pressure to a specific situation. Hopefully that makes some sense.....lol

In this context you always use "the pressure". Perhaps there is no satisfying answer. Perhaps it is because there is such a strong focus on the fact that in this situation the person experiences such pressure, that has some result. So we use the definite article. I am at native level, but had to learn English myself, I can advise just to mimic some things, especially phrases, and hey will become second nature,