Cyrene takes training her students very seriously. Miles wasn't showing the kind of enthusiasm Cyrene was hoping he would.
Clearly, Miles needed a bit of intense encouragement.
Miles first encountered Cyrene after he tuned into Lapis' latest stream only to see Vera getting utterly dominated in a Sparring Match by this mysterious woman.
Before this moment, Miles has always assumed that no one could escape Vera's wrath, let alone beat her in a fight. It was then that Miles decided to ask Lapis to introduce him to Cyrene so that she could train him to become strong enough to fight off Vera. Cyrene agreed to train Miles and invited him to her gym to start training over the weekend.
Of course, Miles wasn't a very passionate kid and was best described as "laid back" in attitude. This isn't impress Cyrene very much who knew that Miles wasn't giving this training his everything.
Cyrene knew the only way to train Miles was to push him to his limits, And then push him a little more.