不入虎穴，焉得虎子

one who is not prepared to risk his child will never catch the wolf (proverb); (fig.) one who is unwilling to take risks will not achieve great things

lit. to willfully go towards the mountain although knowing that it has tigers (idiom); fig. to take a risk despite knowing the dangers

lit. you can't gain knowledge without practical experience (idiom); fig. wisdom only comes with experience

no pain, no gain (idiom)

lit. newborn calves do not fear tigers (idiom); fig. the young are fearless