Imagine there's some body and a force F trying to move that body. In that case the force will do a work and the body will start to accelerate (obtain a kinetic energy). Now also imagine that I'm applying a force -F right in the opposite direction of the existing force, when the body is still standing. Then it will remain standing as long as the 2 opposite forces are applied and cancel each other. Question: Do I do some work or spent some energy while applying that force -F? If yes, then is there a formula for it, if no, then does that mean, that it's the same whether I do nothing or try to hold the body from moving by applying an equal force to the existing one but in opposite direction?