Pressure and stress are not the same thing. But the former is converted into the latter when you add one ingredient: rumination, the tendency to keep thinking about past or future events in a negative way.
When you start ruminating (you’ll notice that your attention gets caught in an unproductive loop, like a hamster on a wheel), redirect yourself toward areas in which you can take useful action.
Try this exercise: Draw a circle on a page. Write down all of the things you can control or influence inside the circle and all of the things you cannot outside it. Remind yourself that you can care about externalities (your work, your team, your family) without worrying about them.
You can also put things in perspective by comparing a past stress with a current one — i.e., a major illness versus a missed sale — or by asking yourself “How much will this matter in three years’ time?” or “What’s the worst that could happen?”