Brain Surgery
Very often the experience of practicing mettā feels like a brain surgery. This is not a metaphorical statement; I can feel the changes going on the physical level in my body.
The subtle mental aspect of our being and the gross physical level are intertwined. One affects the other. The chanting of mettā mantra operates on both the mental, psychological, and material, physical level. Very often I can feel parts of my brain relaxing tension. This has in turn the effect of clarifying the sensual perception and also the decrease of egotistical "I" making.
Yes the ego creates mental tension by blocking the flow of prana or life energy. We feel much more aliveness and vitality by not having an elaborate ego.
So Buddha's path is not mere philosophy and empty rituals — it is a mental surgery that tackles our "I" making and eradicates it without the reminder. Happiness increases when the ego dies. Happiness that's an intrinsic feature of our very being.