According to Osho, shunya is not nothingness but the whole; practice is needed to dissolve the false, separate 'well' into the ocean of being. Sadhana - awakening the inner energy (kundalini) and opening your inward channels - returns you to the ocean, ending ego-born sorrow. You gain nothing; you relinquish the lie of separateness and, in dissolving, become the vast.
You practice to melt your small, separate self into the big ocean of life—you don’t disappear; you become everything.