How can I get used to breathing through my nose instead of my mouth?

Hmm fill your mouth with water/juice.

…have a sipper with you always.

Or still easy u can just fill ur mouth with air like a toad.

So read my other answers if your breathing problem is chronic or has been there for more than six months for a holistic solution.

Off late i also found something called Salt room therapy. While relaxing in one of treatment rooms, customers inhale the dry, salt-enriched air deep down into the lungs, where the healing benefits do their greatest healing. The salt loosens the mucus, which begins to clear quickly, and inflammation is reduced, which makes more room in the airways for you to breathe. Symptoms subside, sometimes for up to 12 months.

Dry salt air is more powerful than moist air. The negatively charged ions in salt improve our health and mood. Inhaling particles may reduce inflammation and mucus in the lungs, improving most respiratory conditions such as asthma, allergies, bronchitis, sinus congestion and Chronic Obstructive Pulmonary Disease (COPD).

See if you have it nearby or see if you can customize, like use a nebulizer at home. BUT MAKE SURE YOU KNOW HOW TO PREPARE THE RIGHT SALT WATER OR SALINE SOLUTION. PLUS ENSURE ITS HYGENIC AND YOU HAVE CONSULTED A DOCTOR WHILE CUSTOMIZING YOUR SALT ROOM THERAPY USING A NEBULIZER AT HOME.