Success is ...
 

Quote from Winston Churchill:

Success is walking from failure to failure with no loss of enthusiasm.

¿El éxito consiste en andar de fracaso a fracaso sin perder el entusiasmo?

Quite well!!

To give it even a more Churchillian style in Spanish:

El éxito es ir de un fracaso en otro sin que el entusiasmo merme.

(remember that Spanish uses subjunctive and imperfect a lot when something is described as an on-going process: "ir de un fracaso a otro")