If you are pushing a wall but there has not been done any work done.How do you know that its obvious formula we have.
WORK DONE=APPLIED FORCE ✖ DISPLACEMENT
you are pushing wall constantly but wall does not move that mean no displacement has been done by you and if displacement is zero then what work done by you would be zero.
But you were constantly pushing the wall that mean some energy has been spend by you on pushing the wall but there is no work done made by you.So where is your energy which has been spend by you on pushing the wall?
Let discuss it think about the law of conservation of energy we can not produce energy neither we can destroy we all are familiar about the third law of Newton Every action has a reaction" so when you were applied a force on wall for pushing it at the same time wall also exerted a equal and opposite force on you so you all energy has been spend by this oppisite and equal force which was exerted on you by wall.