A more complete title would be "The struggle to overcome the problem." It is part 4 of 5 in my "Five Parts of Story."
This section takes up the bulk of most stories, and partly because of this, it is where most stories either really make it happen, or really fall flat.
Luckily there are a few basic guidelines for this area that can really help keep your reader's interest.
1. ESCALATING CONFLICT. Plain and simple, the stakes need to get higher and higher, often until the main character is facing death itself. The choices need to be harder and harder to make. (Hint: not between good and bad--that's easy. They need to choose between one love or the other, saving your wife, or a city filled with 2 million innocent victims). And the physical challenges may become more and more difficult to accomplish as well.
This might sound obvious, but it helps to start your story with simple problems (like what to wear that day) and gradually build to problems so extreme (like life and death types of choices) that the first problem is seen in an entirely new light. If your story doesn't have this kind of rising tension, the tendency is to get bored with the stakes we already know.
2. A CLEAR GOAL. I'm big on characters having very distinct goals. However, it is possible for the short term goals to shift several times during the course of your story. A great example of this is the incredibly popular Wimpy Kid books. I certainly wouldn't try to speak for a master like Jeff Kinney, but the books seem to be fueled primarily by a long series of gags (each with their own short term goals), which all fit within one larger goal of trying to be cool.
In most cases though, having a clear goal can be the difference between keeping your reader until the end or losing them half way through. But let me add this other CRITICAL part to that: we need to know WHAT BAD WILL HAPPEN IF OUR HERO FAILS. It can be stated in one short comment if you want, but it NEEDS to be in there somehow. In my picture book The Monkey Goes Bananas, there are no words describing things, yet through the visuals, we still know that if the Monkey fails to get across that water, he will get eaten by the shark. In movies, it is super common for a character to literally just say the stakes, like "If we don't kill that shark, it will keep eating swimmers forever."