It can get exhausting, but you have to stay focused, otherwise you risk being hit with 3-4 pounds of steel, or poked with a dagger, or both.
You have to try to do it right, both for yourself, and so that your partner can do their part properly. It’s fine if you make a mistake, everybody does, and you’re learning. Just keep trying to do it right.
You have to listen to the teacher telling you what to do. If the teacher is telling your partner what to do, you have to be observant of your partner, and respond properly.
You and your partner are like dancing partners. You have to respond to each other’s moves, to adjust, to dance around each other, to create beauty together. Even if it’s often a clumsy kind of beauty.
During a fencing lesson, nothing else exists. There are no outside worries. There’s no room for them. There’s no breath to spare.
There’s only fencing.