Learning.
For many people, it is a troubling affair.
It's very common to encounter difficulties during the learning process, which may stem from various factors, including the complexity of the knowledge, learning methods, psychological state, and environmental influences.
Everyone knows that progress is necessary.
But not everyone can accept the suffering that comes with learning for the sake of progress.
The fundamental pain of learning lies in the poor ratio of input to output.
When learning new knowledge or skills, it often requires us to understand and master complex concepts, theories, formulas, languages, etc. These contents may exceed our current cognitive scope and require a great deal of energy to think, ponder, and practice repeatedly.
In the end, we might not gain much.