Pick two endpoints in the room โ couch and wall, kitchen and door. Nothing else.
Walk to one end. Touch it. Run to the other end. Touch it. Run back. Look at them expectantly.
A 2-year-old will run the same loop twenty times. A 4-year-old will invent variants โ hop, crab walk, backwards, eyes closed, lava floor.
Add a count ("how many times can you go?"), or call out an animal for each leg ("bear to the couch, frog back").