A fitness trail is like a big outdoor playground where grown-ups can exercise and have fun at the same time! It usually has lots of different stations, or areas, where you can do different exercises like jumping, balancing, and stretching. Each station has a sign that tells you how to do the exercise and how many times to do it. It might also have things like monkey bars to swing on or a bench to do sit-ups on. You follow a path around the trail and do all the exercises at each station to get a full workout. It's like playing a game, but you're also getting stronger and healthier!