Okay, I would like to preface my advice by saying that I am not particularly intelligent, not educated in a technical field, nor do I write nearly as often as the other posters. I do, however, play a lot of tabletop role-playing games. People who play in these kinds of games often tend to develop an understanding of motivation so they can react in the moment to the unfolding game. This is especially true for the Game Masters because they have a much larger number of characters to run, and pre-planning their actions is not really feasible.
All the advice so far from the other posters pretty much boils down to get into the character's head and see what makes them tick, like taking apart a mechanical watch and seeing how each part interacts with each other and produces a predictable result. To draw out the metaphor, this kind of analysis only works if you understand what a gear does, the physical properties of a spring, the increments of seconds, minutes and hours. If all you know is that this device is meant to convey some kind of information on its face, figuring it out from the ground up is bound to be somewhat daunting.
Instead of looking out, perhaps try looking inwards. Do some basic role playing exercises. Take a situation, place yourself in it, and react. Once you have made a decision, stop and work it backwards; keep asking why. Keep breaking down each step in the decision tree, asking why you made that decision, what specific factors led to it. The goal here, to reach back to the metaphor, is to look into your own watch and identify all the parts. They may not be the same size and shape as another person's, and they may not fit together in the same way, but they have similar properties so once you know what kind of things are in yours, figuring how it all goes together and interacts in someone else's becomes more feasible.
If possible, working with someone else to set the scene might be helpful. Not only does it open up possibilities that might not occur to you, it provides a person to serve as a mirror. It is hard to accurately see yourself without something outside of you helping.
All the advice so far from the other posters pretty much boils down to get into the character's head and see what makes them tick, like taking apart a mechanical watch and seeing how each part interacts with each other and produces a predictable result. To draw out the metaphor, this kind of analysis only works if you understand what a gear does, the physical properties of a spring, the increments of seconds, minutes and hours. If all you know is that this device is meant to convey some kind of information on its face, figuring it out from the ground up is bound to be somewhat daunting.
Instead of looking out, perhaps try looking inwards. Do some basic role playing exercises. Take a situation, place yourself in it, and react. Once you have made a decision, stop and work it backwards; keep asking why. Keep breaking down each step in the decision tree, asking why you made that decision, what specific factors led to it. The goal here, to reach back to the metaphor, is to look into your own watch and identify all the parts. They may not be the same size and shape as another person's, and they may not fit together in the same way, but they have similar properties so once you know what kind of things are in yours, figuring how it all goes together and interacts in someone else's becomes more feasible.
If possible, working with someone else to set the scene might be helpful. Not only does it open up possibilities that might not occur to you, it provides a person to serve as a mirror. It is hard to accurately see yourself without something outside of you helping.