The pain in math comes from trying to solve problems you know are solvable. Either doing exercises, or deriving a result some article called trivial. Compare t

The pain in math comes from trying to solve problems you know are solvable. Either doing exercises, or deriving a result some article called trivial. Compare this to doing original work. Here, when you get stuck it is frustrating because you want progress, but there is no reason to presume that what you are doing is feasible. Therefore, it is not painful that you make no progress, for it is not expected of you to be able to progress. This is of course a big difference between undergraduate mathematics and doing mathematics research.