Some of my favorites:

The anvil fears no blows.

What is hard to endure is sweet to recall.

There are many wrestlers who have competed without great knowlegde or skill, but none have ever wrestled without pride.- Dan Gable.

Some fun ones:
A closed mouth gathers no foot.

Never test the depth of the water with both feet.

It makes no sense to clench your butt cheeks after you have already farted.-Japenese proverb.