I think this question may have been asked before.
While concentrating on the spiritual eye, invariably some pressure or tension is felt in the region between the eyebrows. Sometimes it is intense, troublesome and unavoidable. There is tension even when the eyes are not physically pointed there. Not much mention is made how to avoid this or if this is a problem at all. It is meant to be pleasant isn’t it?
Could you elaborate on why its an integral part of yoga and how to make it natural?
Tension and pressure at the spiritual eye is a common complaint. A complete discussion goes beyond a simple written reply (a personal teacher can be helpful). But start with experimenting with open eyes on where to look.
Look up through the point between the eyebrows and find the "sweet spot" where gazing upwards feels natural and right and good to you.
A few ways to help include extending the arm in front of with thumb upward and looking at your thumb. Or looking up to where the ceiling meets the opposite wall. Then, close your eyes and hold your gaze steadily upward.
Emphasize relaxation and thus de-couple the common connection between concentration and tension. When we enjoy what we do concentration requires no tension.
Feel that it is natural to look up. For some people concentration at the point between the eyebrows is aacompanied by a physical response in the area which produces tension. Relaxation is the key!
Only in the more extreme cases of tension might it be helpful to focus upon the heart center (at least until the tension recedes). More could be said but start with these suggestions and we can go from there. Ok?