Inefficient exercise is quite effective for whipping you into shape.
Example:
Driving your car for 1 mile = efficient
Running uphill for 1 mile = inefficient
Inefficient moves make you work. Ideally, in a safe and repeatable manner.
Done with good form and aggressive intent, heavy kettlebell swings fit the bill. When you pair them up with floor-based work like push-ups, you have a recipe for smokin’ buns, guns, and lungs.
Let me demonstrate: