Please choose the correct ending to complete the given sentence: Health: [header] How to stop mouth breathing [title] Try to breathe through your nose for 2 minutes. [step] Close your mouth, watch a clock, and try to breathe through your nose for 2 minutes straight. If you have issues doing this, it probably means that you have a clogged nose and the cause of your mouth breathing is physical or structural rather than habitual.

Ending1: Be aware of whether you are having trouble breathing because your body is trying to expel a foreign substance by making certain chambers in your nose full of gases. [title] Try to breathe through your nose for four minutes. Ending2: [substeps] Two minutes is approximately the number of breaths you should take per minute. If you have trouble breathing through your nose, try checking a watch to see how many seconds tick by. Ending3: [substeps] If you have a history of mouth breathing, it is something that you should avoid. If this is the case, you should not carry your breath into your mouth as it can slow down the movement of air in the lungs. Ending4: [substeps] If your mouth breathing is caused by a structural or physical issue, you'll need to investigate further and get diagnosed by a doctor. If you have no issues breathing through your nose, then it's a habit and may be easier to fix.

Answer format: ending1/ending2/ending3/ending4