The wise does at once what the fool does at last.
If you've got a talent, protect it.
It's always too early to quit.
If you can dream it, you can do it.
I can, therefore I am.
Well done is better than well said.
Who seeks shall find.
The dog that trots about finds a bone.
Be kind whenever possible. It is always possible.
Know or listen to those who know.
In hard-core science fiction in which characters are responding to a change in environment, caused by nature or the universe or technology, what readers want to see is how people cope, and so the character are present to cope, or fail to cope.