Need to take into account different body types, and whether the goal is to burn calories or not. Whether there is time gained or not. Say, walking is evidently

Need to take into account different body types, and whether the goal is to burn calories or not. Whether there is time gained or not. Say, walking is evidently more efficient than running. Why do people run then? Because circumstances demand it; because they like to stay or get into shape, because they want to burn fat, because they enjoy a change of pace, or because they need to catch a bus. Or simply: because they can / find it fun (children). Speaking of children: hopping is the most efficient form of movement for small children (IIRC around the age of 6).