For me to hold a heavy object stationary in air is tough and eventually I will get tired. So it seems I am expending energy. But then how much? I discovered it was quite hard (for me anyway) to calculate how much energy it costs to hold the object when there is no work. The only thing I could come up with requires knowledge about the system that is creating the force that opposes gravity. I suppose if you can determine how much power is going into the system and how much is going out then the difference is what it costs (J/s) to create the force to hold the object per unit of time. Is this really the only way to do it? It seems like there should be a better way because this is more like an efficiency calculation and I know different system would require different amounts of energy (per unit of time) to create the same force. I have a hunch I am missing something fundamental or making a mistake in my reasoning. Am I right?