Exercising the will to truly live - and also truly die - makes for the slightly abstract theme in English actor Andy Serkis' directorial debut, Breathe.
But with the very watchable Hollywood name Andrew Garfield as lead character Robin Cavendish in this life-affirming film partly disguised as a weepie and romance, bums should surely find themselves on seats.
Garfield, fresh from his lauded turn as a missionary from another gut-wrenching film, Silence, replays the life of a paraplegic who defied all medical odds and escaped from institutionalised care to pioneer the modern development of wheelchairs equipped with mechanical lungs.
Cavendish's work today is recognised as having helped pave the way for a more humane treatment of the severely disabled in the field of healthcare.
"It's about laughing in the face of adversity. It's the human spirit of longing to live," Garfield says.
"To do what you want to do versus what you're meant to do."
Cavendish, who was born able-bodied, lost the use of his body at the age of 28 at the height of his career, after he caught polio while on a trip to Kenya where he had been working as a tea broker.
Only just married to a young woman, Diana (played by The Crown's Claire Foy), the man survived his last-minute diagnosis and emergency hospitalisation to see the birth of his son, Jonathan (who, not so coincidentally, produced the film in honour of his father). Cavendish was sent back to Britain, where he was chained to a mechanical lung while incarcerated in a care institution, expected to live no longer than another three years.
But the man refused to be confined to his bed - or fate.
Director Serkis points to a pivotal scene in the movie: "Diana asks in exasperation, 'How can I make life better for you?'
"And his answer was, 'Get me out of here.'"
And so, a naughty little escape plan was hatched, followed by a series of imaginative D-I-Y extensions to a wheelchair.
The morose subject matter for a film began to provide foil for a jaunt in optimising clever props for cute little set pieces extending as far away as a plain in Spain in a bespoke caravan, even as Garfield began training with Serkis in specific, small-scale facial movements.
"I had help, though, from the make-up department," the actor says. "Towards the end, when I had to be aged, they taped down my lids to simulate the effect age would have on my eyes. Really made a difference. But everything I could do with my eyebrows, I learnt from Andy."
Indeed. One would imagine Serkis - better known as the face and body behind the animated special-effects character of Gollum in The Lord Of The Rings - to be the best teacher for Garfield.
Make no mistake, however: Do not call him a motion-capture actor (he also did motion-capture work on King Kong in the eponymous 2005 film and as the ape Caesar in The Planet Of The Apes reboot film series).
"No such thing really exists," Serkis says. "Acting is just acting. Authorship of the role takes place on set."
What the director will tell you instead is about how his vicarious experience in the medical world - growing up the half-Iraqi son of a field doctor who stayed as long as he could in the Middle East working under difficult situations of conflict and having a mother who taught in a special-needs school - prepared him for the film.
"Growing up in this environment, I had some understanding of polio," he says.
Apart from intimate knowledge of the lives, routines and needs of disabled people, he felt he could also empathise with Cavendish on a deeper, societal level.
"I was brought up in England, but maintained Iraqi connections and visited every year - until I could no longer do so," Serkis says. "It made me both an insider and outsider to England and Iraq."
"Robin, too, became an outsider - to his own life."
For Serkis, what kept Cavendish going was, on one level, the stubbornness and refusal to surrender to his prescribed fate.
As the film progresses towards its poetic and poignant ending, he makes a difficult decision that reflects his ability to take agency of his life and, paradoxically, allow for the release of the agencies of the lives of the people he cared about most.
In other words - a kind of love.
"In an era where you meet under the conditions of Instagram and with a younger generation that's so used to seeing their parents divorce, the idea of staying with someone all the way till the end, however you choose it, might feel like an alien concept," Serkis says.
"But it's about transcending romantic love, into true empathy."
Garfield adds: "It helps you look at life differently. And it trains one to be self-knowing. Cavendish was truly self-knowing, self-aware.
"He became a spiritual person. His whole family came up with an excellent template on how to live. They figured something out."
For all the heavy-duty proclamations of triumph of the human spirit, however, there were one or two light-hearted moments.
In scenes where Garfield had come out of depression and had to interact with his partly estranged one-year-old screen son, it was crucial that the crew captured the child's rouse of delight on film when he met his father again.
Here, it was not good acting nor tapping into universal love and empathy that did the trick.
The answer: Peppa Pig.
"We'd hold an iPhone directly under my chin," Garfield confides.
"And at the opportune moment, we'd switch it on and the kid's face would just light up like a million dollars."