Here are some motivating quotes I came across with during my studies so far:

“If I have 300 ideas in a year and just one turns out to work I am satisfied.” -- Alfred Nobel

“If I have done the public any service, it is due to my patient thought.” -- Isaac Newton

“The road to success is always under construction.” -- Lily Tomlin

“It is infinite alone that cannot be attained, for if it could, it would become finite.” -- Leonardo de Vinci