It's always too early to quit.
Things do not happen. Things are made to happen.
What you do today can improve all your tomorrows.
Be thine own palace, or the world's thy jail.
Be gentle to all and stern with yourself.
To be a good loser is to learn how to win.
The dog that trots about finds a bone.
If you can dream it, you can do it.
Without hard work, nothing grows but weeds.
Problems are not stop signs, they are guidelines.
If you always put limit on everything you do, physical or anything else. It will spread into your work and into your life. There are no limits. There are only plateaus, and you must not stay there, you must go beyond them.