Live like 'the highest good - water, taking whatever shape needed': keep your principles but stay flexible.
Tips
history
The first four characters 上善若水 come from 《道德经》 ch. 8 (Laozi): 上善若水。水善利万物而不争. The added 任方圆 is a later elaboration widely used in calligraphy and modern quotation, meaning water lets the container determine its shape without losing its nature.
usage
任 here = 'let / allow,' not 'responsibility.' 方圆 = 'square or round,' i.e. whatever form the container imposes.