This question is challenging but rich. To use Hamlet to begin a reflection on the relationship between the external and internal worlds, the soliloquies are your best start. Hamlet has several soliloquies, and they are the most impressive element in the play (at least in my opinion). Each one is prompted by an external event that challenges Hamlet's sense of his world or his own character. Through these, we see Hamlet's mind at work, growing in response to the events that unfold in the play. Prior to each soliloquy, Hamlet experiences something distressing, which he then thinks about and voices in these meditative speeches. These, along with the "Alas, poor Yorick" scene, illustrate a mind contemplating injustice, death, and despair. The path Hamlet takes is not linear so much as it is a spiral, and with each event, Hamlet learns and adapts to his external situation. In act 5, he comes to a measure of peace. "To be, or not to be" becomes "Let be," and he seems in possession of an inner acceptance that was not present in the earlier acts of the play.
Another text that might be interesting to explore in this regard is J.D. Salinger's The Catcher in the Rye. Like Hamlet, Holden (Salinger's protagonist) is coming to terms with the complexity of the adult world, with change, with death, and with his own fear of losing his integrity, of being a "phony." In Holden's idiosyncratic narrative of his strange odyssey thought Manhattan, we find a similar movement toward peace that comes from giving voice to the despair events provoke. Only by speaking of these events though his long monologue can Holden give shape and meaning to the external events he experienced and how they influenced his thinking.
Since the assignment seems to require a personal response, try to find an experience where an external event prompted a series of thoughts that affected your view on the world, on a set of problems or issues, or even on your own role in the world. Then use your texts to find points of contact that help illuminate that shared experience.