At my job, the second floor is pretty much a grate, and I can kneel on it, put a leg down on it, sit on it no problem for an extended period of time. Everyone else is always like, "How can you do that? Doesn't it hurt?" and they use these pads that they put under their bodies so they can't feel the grate.  No it doesn't hurt, I don't have all that weight pushing down on it like all you fatasses do.