The core of his argument lies in this concept: that the "key element of an optimal experience is that it is an end in itself. Even if initially undertaken for other reasons, the activity that consumes us becomes intrinsically rewarding" (67). A "self-contained activity, one that is done not with the expectation of some future benefit, but simply because the doing itself is the reward," is key to what Czikszentmihalyi refers to as an "autotelic" experience, meaning, a self-motivated goal or activity. Even the most painful or difficult experiences, he argues, can become rewarding if the person sticks with it long enough to have that proverbial lightbulb go on.
That means that if you're not enjoying something actively, but you stick with it, the chances are much better that you will have that moment of inspiration or breakthrough that leads to the next place in your understanding, ability, or talent with something. The preparation is all. The amount of work, conscious or unconscious, that you put into something (like writing, obviously) can lead to greater insight and skill.
One of the things that makes sense is that writers must be readers, must immerse themselves in the printed, written, and spoken word. To enjoy writing... for it to flow for you, might not happen overnight. I doubt it happens for very many writers. It isn't enough (in my experience, working with published writers as their editor) to get accolades, money, and fame, from your writing.
To love to write... this is part of the process, and it might not be obtainable. But if you read Csikszentmihalyi, you will get a better idea of how it's possible.