What do you do under pressure? Lots of people do things differently, some will quietly stress, others become more verbal, irrational thoughts can kick in. Before long if the pressure is great enough things can explode. How that looks depends of the level of pressure, the situation and the personality of the person/s under pressure.
In business the pressure can be so many things, not enough turnover, staff not performing well, suppliers wanting payment, customers doing what customers do… and the list rolls on.
Your challenge becomes how to handle that situation. I guess in an ideal world a highly capable person would know how they normally act under pressure and aim not to respond in that way, instead choosing some form of positive response (especially if it has solidly negative outcomes)
If you are not able to snap your fingers and create a more positive situation for yourself, then working with pressure is something you need to figure out. As they say prevention is better than finding a cure, so your task iis to assess what the challenge/s are and tackle them with the aim of making them stay at bay.
Perhaps start with a list of key areas of your business and what’s causing the pressure to build, then jot down some responses to minimising the challenges. Even a very simple approach like this can make a world of difference, in essence you state the problem on paper and get it out of your head, enabling you to focus more on the problem and possible solutions.