1. Make an A shape with the index and middle fingers of both hands, and make a fist with the remaining fingers.

2. Tighten your lips inward and cover the entire teeth at the same time. Try a few more times to find out how far your lips need to be inward.

3. Remove the tongue and use your fingers to move the tongue inward. At the same time, gently press the tongue downwards. The tongue will appear arched.

4. There should be a finger in the mouth and exhale through the hole formed by the mouth.