We have a quadruple bonus quote today, for reasons that will immediately be evident:

Dream as if you’ll live forever, live as if you’ll die today.
- James Dean (1931-1955)

Live as if you were to die tomorrow. Learn as if you were to live forever.
- Mahatma Gandhi (1869-1948)

Sic vive tamquam cras moriturus, sic stude quasi semper victurus
(Live as if you were going to die tomorrow, learn as if you were going to live forever).
- Desiderius Erasmus of Rotterdam (1466-1536)

Imitation is the sincerest flattery.
- Charles Caleb Colton