Doing these things is called discipline. And yeah — discipline is a challenge. Which is why few people have much to spare, let alone have any at all.
Conversely, it’s hard to relax when you’re facing a challenging task, or to be the face of calm when everything around you is going haywire. This is the flip of the same coin: discipline.
One trick of many is to do the hard stuff as if it were easy — calming your mind, reminding yourself how many times you’ve already done this.
You can also do the easy stuff — the things you’re most likely to mess up due to your lack of urgency because you’ve done it successfully before — as if they were difficult. This brings focus and attention to detail.
All of this is in the name of tricking your mind into believing something different from what’s actually in front of you. Your brain will not know the difference, and will do just as you tell it.