Preposition for the verb focused

The following article is written by someone who is not a native speaker but teaches english. My question is only about the use of the underlined word. "Kristin felt unjustly treated. Knowing that she was too upset to make sense, Kristinfocused all of her energy into calming down. Once she felt calm enough to move, she turned and left, telling Barbara, “We’ll talk in the morning. I’m late for my tennisgame.” But after leaving the office, she was still trembling. The subsequent tennis game — hitting those balls — was exactly what she needed to become completelycalm." I told him that the underlined word is not correct and has to be changed into ON but he keeps insisting that the sentence is correct. I am confused now. Can the word "into" be used there because of the context? Or ON is the only possible option to be used. Could you help me clarify it? Thanks.