One of the best examples of steadiness may be biathletes, who have to ski like crazy then stop and accurately shoot a rifle. Supposedly they time their shot as they are exhaling, and between heartbeats for the best steadiness.
Except for a Jedi, this may be the best we can do.

Actually, timing a shutter release this way is not that difficult with practice and concentration but all that goes out the window when Cinderella or the Mouse walks into view!