Growth is painful because you have been avoiding a thousand and one pains in your life. By avoiding, you cannot destroy them - they go on accumulating. You go on swallowing your pains; they remain in your system. That's why growth is painful: when you start growing, when you decide to grow, you have to face all the pains that you have repressed. You cannot just bypass them.
You have been brought up in a wrong way. Unfortunately, until now, not a single society has existed on the earth which has not been repressive of pain. All societies depend on repression. Two things they repress: one is pain, the other is pleasure. And they repress pleasure also because of pain. Their reasoning is that if you are not too happy you will never become too unhappy; if joy is destroyed you will never be deep in pain. To avoid pain, they avoid pleasure. To avoid death, they avoid life.