The more frustrated, the braver.

If you don't advance, you will retreat. -Liang Qichao

Difficulties and setbacks may be beneficial. This is a kind of exercise, which is my motivation to move on. -Xian Xinghai

Only difficulties can make people show their true colors. -epiktetos

The most difficult time is the day not far from success. -Napoleon

Difficulties come, some people soar because of it, and some people can't afford to fall because of it. -Tolstoy