I don't mean by walking out into the sunlight, blinking, while you talk about the special effects and jokes while fumbling for your lighter.
Rather, by feeling so moved by what you have seen, so connected to the characters portrayed on screen, that you sit there, not wanting to move, not wanting that feeling to end.
So it was with Lore.
Based on Rachel Seiffert's book The Dark Room, Lore (pronounced Laura) tells the tale of a family of children attempting to make it across Germany in the days after the fall of the Third Reich. Their parents have been captured, the world is in chaos, and all they have is each other as they attempt to make it to the safety of their grandmother's house.
On the face of it, not a fun frolic through the Fatherland. And it's not.
It's a stark, harrowing tale as children too young to understand have to face up to a world that is changing. From being members of a favoured family, high-up in the regime, they are forced to scavenge and scrape by as the conquering forces divide the country up.
But it's also wonderfully compelling, drawing you in instantly and never letting you go.
There are two things that give this film the emotional impact it has - how it is shot, and how it is performed.
Now, normally, the phrase "it looks lovely" is critical shorthand for "there's nothing going on here", but that's not the case with Lore. The filming is so lush, and some scenes so moving, that it underlines the stark reality of life for Lore and her family. Rather than covering up shortcomings, director Cate Shortland has used deft brush strokes to enliven and enhance the story.
But all that would be for nowt if it wasn't for Saskia Rosendahl. Not even 20 when Lore was made, and in only her second film, she shines as a young girl forced to take on responsibility for her family.
Through her you feel the hardships, the cultural shocks, and it is a measure of her performance that you don't hate her when the instilled Nazi hatred and dogma comes to the fore.
I honestly can't remember the last time I felt so moved by a performance.
But she's not alone in capturing a raw, honest, harrowing portrayal of youth forced to take on a world created and destroyed by adults.
Alongside her is Kai-Peter Malina, of The White Room fame. Here he plays a young man on the run using Jewish papers, who teams up with Lore to effectively take on the father's role of finding food and shelter. He creates the perfect foil for Rosendahl, allowing her space and focus as Lore battles with reality, while at the same time leaving his own impression on the audience with a performance that is beautifully subtle and understated.
I'll admit, sitting there watching children fighting for survival as the world they knew is torn apart by powers beyond their comprehension and control will not be everyone's idea of a great night out - but this film is strangely heartwarming and uplifting.
Yes, Lore is entrenched in the Nazi mindset, yes her younger brothers are well-drilled Hitler Youth boys, yes she learns ways of getting what her family needs that she should have been shielded from - but is any of that really her fault?
Well, that's ultimately for you to decide.
All I can tell you is that as the credits rolled, I just wanted to watch it all over again.