Why is this the answer?

The answer is thorn because this is a super clever riddle that uses tricky words to describe something very small that can cause a big problem, especially when you are walking outside. A riddle like this is a puzzle that tells a story, and we have to figure out what tiny thing the story is about. The entire story is about how you deal with a small, sharp piece of a plant that gets stuck to you. Let us look at the first part of the riddle, which says, "I walked and walked and at last I got it." When you are walking through tall grass, near rose bushes, or in a park, you might accidentally step on a thorn. You do not stop to pick it up or look for it; instead, it catches on your shoe or pokes into your skin all by itself while you are busy walking. It "got" you without you trying to catch it. The second clue makes perfect sense: "I didn't want it." Who would ever want a sharp, painful thorn stuck to them? Definitely no one would wish for that. The thorn is an unwanted little troublemaker that causes pain and makes you uncomfortable. Now for the next part of the story: "So I stopped and looked for it." If you feel a sharp poke in your foot from a thorn, you cannot keep walking. That would hurt too much. You have to stop immediately, sit down, and check your foot or shoe very carefully to find the tiny thing that is causing the problem. You are looking for the thorn so you can get rid of it. Finally, the riddle says, "When I found it, I threw it away." Once you finally spot that small, sharp thorn and pull it out, you would not put it in your pocket or keep it. It is just a little piece of plant that hurt you. So, you just toss it onto the ground and happily keep walking, feeling much better that the annoyance is gone. The whole riddle describes the surprise, unwanted arrival and quick disposal of a bothersome thorn.