According to Osho, to be grown up is not to age horizontally but to rise vertically in consciousness. It means deepening your roots into your own being—becoming more alert, silent, peaceful, loving—so inner depth balances outer height. Such maturity is self-evident, like a migraine: only you can know it. Everyone grows old; only buddhas truly grow up.
Growing up means going deeper inside with awareness and silence, not just getting older, and only you can feel it.