Every celebrity works hard; okay, maybe not as hard as a Chilean miner or a member of the military, but they really do put the hours in. If you factor in pre-production, the actual filming, any post-production work and the months of press junkets, a film can take almost two full years to make. To one degree or another, all stars work hard. Making films itself is hard: you spend countless hours on boiling hot sets repeating the same motions over and over again, whilst still trying to make it seem like it's natural and the first time you've performed it. There is something to be said for the kind of actor who just doesn't stop working - either because they really love working, or because they believe in the projects, or maybe because they just like money. Personally, I'll never get sick of seeing Sylvester Stallone or Robert De Niro in films, but there is a risk of over-exposure - just ask Lady Gaga, isn't everyone sick of her now after her being everywhere in the past few years? Anyway, here are 10 actors or actresses who we think are the hardest working. It's entirely based on how much they put into their performances, not necessarily their box office grosses.