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Make a surprised "O" shape with your mouth, keeping the "O" fairly tight. Place an index finger on either side of your nose, one on each nostril. Push each nostril in about halfway toward your nose; you need to still be able to breathe through your nose for this exercise. Turn your head upward. Breathe deeply and blow air out through your nose, flaring your nostrils as you do.  Do this at least 3-5 times in a row to get the full results and repeat it several times a day. It make take a couple of weeks up to several months to see results! Smile as widely as you can; do a big, goofy grin. As you do, push the bottom of your nose upward. Alternate between smiling and going back to your resting face, pressing on your nose the whole time. This exercise may feel kind of goofy, but smiling that wide can also put you in a better mood!  This works the muscles around your nose, which may help slim it. Do 2 sets of 15. Use your index finger and thumb to grasp the bridge of your nose. Then, press up on the bottom of your nose with your other index finger. Keep these in place as you stretch your upper lip down. Alternate between relaxing and pulling your lip down.  This exercise may seem a bit odd with so many fingers on your nose, but it can help work the muscles around your nose! Try 2 sets of 15.

Summary:
Press your fingers into your nostrils to work on slimming them. Smile and press up on your nose to work your nose muscles. Pinch your nose while moving your upper lip to stretch the muscles around your nose.