According to Osho, when you feel opening and lightness, it signals the beginning of awakening: shadows fall away and a luminous, energetic body of light arises within. The protective mind will sow doubts; do not fight it - trust the heart, which knows. Keep exploring, ideally with a master's guidance, because this subtle, electrical aliveness is truer than the body's seeming solidity.
It means your inner light is switching on; let the mind chatter pass and gently keep going.