this is one :

Dyfal donc a dyr y garreg , which translates to say "if you keep on tapping , the stone with break" … but its meaning is "keep going and you’ll get what you’re going for." – its a posotive/nice one.

another is "Deuparth gwaith yw ei ddechrau" which translates as "two thirds of the work is starting" … its meaning is "once you’ve started something , you’re two thirds there" which is basicly supporting you to keep going.

another ; "dywed yn dda am dy gyfaill , am dy elyn dywed ddim" which translates as "say nice things about your friend , say nothing about your enemy" …

"heb ei fai , heb ei eni" … translates as "that without faults is that that hasnt been born" – meaning , everyone has their faults – no ones perfect.