Excellence

Excellence is the result of
caring more than others think wise,
risking more than others think safe,
dreaming more than others think practical,
and expecting more than others think possible.
- Anonymous

We are what we repeatedly do.
Excellence then is not an act, but a habit.
- Will Durant (commonly attributed to Aristotle)

Success is not the key to happiness.
Happiness is the key to success.
If you love what you are doing, you will be successful.
- Albert Schweitzer

Excellence is not a destination to be arrived at,
but a path of continual attention and improvement.
- Jonathan Lockwood Huie

Further reading: 

When is Your Best Good Enough?

Excellence and Humility

Play to win, but be a good loser