After brushing your teeth every day, your mouth should contain half saliva, not too much, and you can't see water in your mouth when you close your mouth.
Then bite your teeth, let the water filter out through your teeth and then filter it back into your mouth. The whole process takes about 1 sec. The process is a bit like gargling, but the speed is not fast. Then the number of round trips is your age multiplied by 2. Example: 20 years old *2, which is 40 times. Count one back and forth.
My fleshy face is so thin.
Another way is to open your mouth and read a few onomatopoeia words when taking a shower: ah, yi, oh, er, um. Just open your mouth and don't send it. Open your mouth as wide as possible for each word, and then keep it for about 2 seconds to change the next word.
I hope the above two methods can help you. Now try it. o(∩_∩)o ...