First, read the English article below.

Place 1 hand on your chest and 1 hand on your stomach. As you inhale through your nose, pull the air down into your lungs, making sure that your stomach rises. Then let the breath fill up your chest. Hold for 5-20 seconds, then slowly exhale through your mouth until your stomach contracts.  Repeat 5 times. This should help you realize how much air you can take in at a time. It also helps you learn to breathe more deeply. Breathe normally, but watch your diaphragm to see if it moves up and down. Deepen your breaths until you can observe a steady up and down movement in your diaphragm. This helps you learn to inhale more deeply. Your diaphragm is a dome-shaped muscle that is present just below your lungs, at the top of your stomach. Sit or stand in a relaxed position. Slowly inhale normally, counting how many seconds it takes to fill your lungs. Then exhale for the same number of seconds. Add 1 count to both your inhale and exhale, and repeat. Continue to add 1 count to both your inhale and exhale until your stomach rises with each breath. Scientists have figured out that splashing water on your face accelerates bradycardia, or the slowing of the heart rate, which occurs when you dive into water. Your body regulates your heart rate while you're underwater so that you receive the oxygen you need while underwater. Triggering this effect while out of water can help you maximize your oxygen usage. Try to keep the water cold, but not icy. Icy water will trigger another reflex in your body that causes you to hyperventilate, or try to breathe quickly. Hyperventilation will hurt your ability to hold your breath for a long time. 

Now, please write a short abstract for it in Vietnamese. Abstract:
Hít thở sâu. Tập trung vào cơ hoành trong khi hít thở. Kéo dài thời gian hít thở. Vỗ nước vào mặt trong khi nín thở.