If you think you can do it, you can.
If you can dream it, you can do it.
Who seeks shall find.
Leap, and the net will appear.
It's always too early to quit.
What you do today can improve all your tomorrows.
If you've got a talent, protect it.
Well done is better than well said.
Expect problems and eat them for breakfast.
Without hard work, nothing grows but weeds.
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.