If you think you can do it, you can.
The dog that trots about finds a bone.
Quality is not an act, it is a habit.
If you've got a talent, protect it.
To be a good loser is to learn how to win.
It's always too early to quit.
You never know what motivates you.
To know oneself, one should assert oneself.
Go for it now. The future is promised to no one.
The secret of getting ahead is getting started.
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.