Valmiki Ramayana Ayodhya Kanda Sarga 106 Shloka 21

अथ or, त्वम् you, क्लेशजम् born of physical exertion, धर्ममेव righteousness, चरितुम् to follow, इच्छसि यदि if you desire, चतुरः four, वर्णान् castes of social order, धर्मेण righteously, पालयन् governing, क्लेशम् exhaustion, आप्नुहि obtain.

If you so desire to follow the path of dharma acquired out of physical exertion, then bear the trouble of governing the four castes of the social order righteously.