Okay, then. Well, don't press any buttons or pull any levers or make funny faces. Actually, don't move. Stand completely still. Don't breathe. Well... you can breathe, but shallow breaths.
[Clara stands still, slowly raising a hand in a thumbs up gesture with a stiff and amused smile on her face]
I mean one minute you're in 1974 looking for ghosts, but all you have to do is open your eyes and talk to whoever's standing there. To you, I haven't been born yet. And, to you, I've been dead a hundred billion years. [Clara looks at the ruined Earth of the distant future displayed on the TARDIS scanner] Is my body out there somewhere? In the ground?