It’s the same kind of pleasure as with hiking: You hike uphill and it’s tough and you sweat, and at the end of the day the reward is the beautiful view. Solving a math problem is a bit like that, but you don’t always know where the path is and how far you are from the top. You have to be able to accept frustration, failure, your own limitations. Of course you have to be good enough; that’s a minimum requirement. But if you have enough ability, then you cultivate it and build on it, just as a musician plays scales and practices to get to a top level.