The dog that trots about finds a bone.
The secret of getting ahead is getting started.
Who seeks shall find.
Be kind whenever possible. It is always possible.
By failing to prepare, you are preparing to fail.
If you think you can do it, you can.
Problems are not stop signs, they are guidelines.
You never know what motivates you.
Be gentle to all and stern with yourself.
Never complain and never explain.
As for everything else, so for a mathematical theory: beauty can be perceived but not explained.