A smooth sea never made a skillful mariner

सम्पदो महतामेव
महतामेव चापदः ।
वर्धते क्षीयते चन्द्रो
न तु तारागणः क्वचित् ॥

Riches are meant to be enjoyed by great people. Difficulties are also meant to be overcome by them. They are the ones who go through lots of ups and downs in life. The moon grows and shrinks whereas stars remain the same.

The virtue of adversity is fortitude.
A smooth sea never made a skillful mariner.
Prosperity tries the fortunate; adversity the great.