Time- The system of those sequential relations that any event has to any other, as past, present, or future; indefinite and continuous duration regarded as that in which events succeed one another.
Time and timing are very important things to consider in stories. If your story is taking place in the real world, then time needs to be well thought out. If your story takes place in the medieval times, then your hero can't use modern stuff. And if your story takes place in modern times, then your characters can't have a sword fight. If you're writing fantasy, then you don't have to worry about that aspect of time. But in any genre, you should make sure that your timing is realistic. Once, I realized that my hero had gone almost a week with no food. Of course you do not have to record every single time your hero eats, but she had been traveling and had no food with her. That was something I had to revise because it was unrealistic to have a teenager go for a week doing difficult training and have no food and limited water. Time is very important!
Trouble- To disturb the mental calm and contentment of; worry; distress; agitate.
Trouble is story. As a writer, your job is to disturb the mental calm and contentment of your hero. Your hero cannot be content! Trouble drives your story because trouble means that the calmness has been disturbed. Just go by the definition! Distress and agitate your hero.
Now, I am done quoting the definition. So when your hero has so much trouble that they either go or are forced upon the story, then you've really started. Trouble not only continues your story, it starts it. Then as the story goes on, trouble builds up and overwhelms you hero, but your hero finds hope.
Pain and suffering build up too, but I'm going to stay on topic!
So when your writer, just keep on throwing issue out at your hero and you can't go wrong! (Well, you can, but it's easier to stay on the right track that way.)
Just one last note on trouble, make sure that it builds up slowly, or else there will be no more things left to do by the end of the story. And also, include a variety of problems.