Well Scientists say if you breathe in to the point were it feels uncomfortable. Then setting your jaw and tell on the tip of your tongue, then THOH it will send vibration through your head awakening your third eyes to this 5 time for 3 days and you should feel something different.
Your third eye is already open. I had a discussion like this earlier. You just need to cleanse and get rid of the blockages. Your third eye is a like a radio once you start to tune it in you will hit the right spot.