Physics is all around us, from the gravity that pulls an object to the ground, to light bending to make a rainbow, to the friction generated by bicycle brakes. In many cases, students go through the day without thinking about the things going on around them. Start to ask students, "What's happening?" whenever you can. For example, if a student spilled some water on the desk, you might spread it out with your hand rather than wiping it up, asking why it will dry more quickly if you do that.
Students might develop an interest in why things happen when they experience things themselves. Your local science museum, or even a children's museum, likely has a lot of hands-on experiments that could spark this inquiry. If that's too far away, bring things into the classroom. For example, you could take the class to the playground and bring different sizes and weights of balls to see which will fall the fastest. Students might be surprised and excited to learn that the heaviest doesn't fall the fastest.
Many students respond to visual stimuli and might appreciate an introduction to physics through videos. You might introduce an idea with a National Geographic documentary or even "Bill Nye the Science Guy." Once children have learned a bit about the topic, they might be ready to design their own experiments based on the ideas. For example, after watching a video on building electrical circuits, students might be able to build their own simple circuits.
Play is a great way for children to learn about physics, often because they don't even realize they're learning. Something simple like plank-shaped blocks allows students to experiment with engineering, especially if you challenge them to make the tallest structure or the longest bridge. If your students are attracted to video games, the website Quark.org has videos and games to teach children about quantum physics, or you could use Minecraft to have students recreate famous structures.