Director James Mangold was a pupil of the legendary filmmaker Alexander "Sandy" Mackendrick (The Ladykillers, Sweet Smell of Success) at CalArts. In a bonus feature on the Criterion disc for Sweet Smell of Success, Mangold talks about a key piece of advice that Mackendrick once gave him:
One of the things that Sandy talked about, just from his own directing experience -- very practical things -- was how you should just walk the blocking of your actors yourself. Because so much frustration on a movie set, and so much angst, can be from this separation that you don't understand the sensuality, what they actually have to pull off with their bodies.
One of his pieces of advice was, "Walk it." Just walk what you're asking them to do, so you feel it for yourself. And he even had this extra thing: "Walk it backwards." If you can't walk their blocking backwards and forwards and understand it, then when their struggling, how can they do it? And certainly, unless you actually put yourself there sometimes, you can't feel it.