Breathing properly

"How long can you hold your breath?" B asked his older sister. She was in her bed, trying to read a book. "I can't. Go away. I'm busy." B climbed onto the bed and pinched his sister's nostrils shut. "B!" She protested in a nasal voice. "Stop that!" B clamped his free hand over his sister's mouth. "B!" Her voice, somewhat muffled by the obstruction, filtered through. "I can't breeeed like dis!" B considered this thoughtfully for a few moments. "Okay," he relented. "Breathe through your belly button."