You never know what motivates you.
It's always too early to quit.
To be a good loser is to learn how to win.
If you're going through hell, keep going.
Be kind whenever possible. It is always possible.
Go for it now. The future is promised to no one.
The most effective way to do it, is to do it.
Things do not happen. Things are made to happen.
After a storm comes a calm.
Always desire to learn something useful.
I am a teacher, and I am proud of it. At Cornell University I have taught primarily undergraduates, and indeed almost every year since 1966 have taught first-year general chemistry.