Without hard work, nothing grows but weeds.
Expect problems and eat them for breakfast.
If you're going through hell, keep going.
To be a good loser is to learn how to win.
To know oneself, one should assert oneself.
Go for it now. The future is promised to no one.
Be gentle to all and stern with yourself.
The dog that trots about finds a bone.
Be kind whenever possible. It is always possible.
Begin to be now what you will be hereafter.
As for everything else, so for a mathematical theory: beauty can be perceived but not explained.