This powerful meditation is challenging, but will give you an experience of releasing yourself from the limits of your mind.  It works directly on the central brain creating a rhythm that activates the area under the pineal gland, allowing it to activate and start secreting the hormones needed to help you break your mental patterns.  This has a secondary effect on the pituitary gland, which then regulates the rest of the hormones in the body, improving your overall vitality (incidentally, this is exactly how mental rigidity works to age us prematurely).

The pineal gland is a gateway to opening new mental pathways, and if it is not functioning correctly or congested you might experience mental rigidity, a difficulty in breaking patterns or experiencing life in new ways. Imbalance in the pineal and pituitary glands can create powerful addictions, entrapments, obessive behaviours.  If you experiencing difficult to break habits or patterns, or distressing mental loops this is an excellent meditation to try
(OCD sufferers please try this and report back your findings). 

40 days is a recommended daily practice to experience the full effect, but depending on how deeply ingrained these behaviours are, or if they are multi-generational, you may want to spend a longer time with this meditation.  It may seem like a long time, but your commitment to break these patterns must be the right level of force to meet the intensity of the pattern you are trying to break.  Show your commitment, stay strong, and push forward past your mental limits!

Full Instructions from 3HO:

Posture: Sit in an Easy Pose, with a light jalandhar bandh. Straighten the spine and make sure the 1st six lower vertebrae are locked forward.

Mudra: Make fists of both hands and extend the thumbs straight. Place the thumbs on the temples and find the niche where the thumbs just fit. This is the lower anterior portion of the frontal bone above the temporal-sphenoidal suture.

Lock the back molars together and keep the lips closed. Keeping the teeth pressed together throughout, alternately squeeze the molars tightly and then release the pressure. A muscle will move in rhythm under the thumbs. Feel it massage the thumbs and apply a firm pressure with the hands.

Eyes: Keep the eyes closed and focus at the Brow Point.

Mantra: Silently vibrate the five primal sounds—the Panj Shabd: Sa Ta Na Ma—at the brow.

Time: Continue for 5 – 31 minutes.