How can the breath be stable?

Hello. You should control your abdominal breathing and exhale evenly. Don't inhale too much, just inhale 70%. So your breathing won't fluctuate. Not necessarily. You should learn to control your breathing with the strength of your waist and abdomen and spit it out evenly. Many songs can't be sung without breathing control. For example, the phrase "Every time I light a match, I see hope, dreams, and my mother talking in the sky" in Match Paradise, and I sing it in one breath. Usually at home, try to inhale air into the abdomen, then put pressure on the waist and abdomen, control the air and then make an "ah" sound, and then inhale, control and make a sound when the air is used up. Practice repeatedly. Find the feeling slowly.