‘Gleason’ is a documentary that could only exist today, the product of a culture filled with seemingly everyone documenting every moment of their lives. The film very much started as that type of personal exercise, before mutating into something infinitely more painful and profound.

However, it’s not in any way a work of narcissism, rather an almost achingly intimate portrait of a man succumbing to ALS (also known as Lou Gehrig’s Disease). The project began as a series of video journals from a father to his unborn son, as rugged and amateurish as that sounds. As the project and the disease wore on, cameras became a more constant presence and the resulting film is both devastatingly powerful and at times nearly impossible to watch. It feels like something that needed to exist for reasons beyond the doc’s personal origins.

Steve Gleason was once an NFL player who made a famous diving punt block that won a game and made him a symbol of perseverance for New Orleans in the wake of the Hurricane Katrina disaster. Steve is obviously the Gleason of the film’s title, but that famous moment and his career get only a passing mention. Shortly after retiring from the sport, he was diagnosed with ALS at 34-years-old. The progressive neurological disease would slowly take away all his motors skills, eventually leaving him in a state where he struggles to breathe. He was given 4-5 years to live. Mere weeks after the diagnosis, his wife Michel learned that she was pregnant. As a result, Gleason decided to start recording video diaries for his unborn son on nearly every subject he could imagine, giving the young child recordings of his father in a state that would seem almost unrecognizable from the man the boy would know.

These diaries make up the bulk of Clay Tweel’s documentary, but most of the life lessons are kept private for that child’s eventual viewing. It doesn’t take long before Steve uses the diaries as a confessional for his own painful physical decline, and it can be gruelling to watch him endure the depths of the disease. At first, he’s seen taking wild travels and participating in all sorts of physical events. Soon, he shuffles and then his speech becomes slurred. He records his voice so that a machine will be able to speak for him in a manner that at least sounds familiar, and he slowly learns to use the eye scanning technology that will become his only means of communication. Whether these sequences are shown through diaries or Tweel’s observational cameras, they’re presented with unflinching honesty.

That Gleason would allow footage so personal to be turned into a movie is fairly remarkable. There are times when the material is so painfully intimate that you’ll want to turn away. You see him fight to spit out his final words and then communicate electronically with almost jarring elegance. His wife Michel struggles with the emotional and physical realities of raising an infant alongside a husband who requires almost as much constant care. Their relationship is depicted wholly and fully with nothing left private. It’s both difficult and inspiring because they’re always able to persevere, even under the most impossible circumstances. Perhaps even harder to watch is Gleeson’s troubled relationship with his father. They’re cordial, but always had issues and the father’s intense Christianity leads them both to a faith healer with predictably painful results for all concerned.

Gleason also uses his celebrity to create a charitable foundation in his name dedicated to ALS. Even in the brief few years of this documentary project, we see the organization achieve some outstanding things. Gleason is so dedicated to the cause that he sadly starts to neglect his family, but soon returns to them. That’s likely the most extraordinary part about Gleason (the movie and the man). Even in the face of unimaginable personal tragedy, he remains driven and passionate, and is determined to help and become a better person. This documentary is unapologetically designed to inspire and does so in ways that earn tears and cheers rather than ever pandering for them.

Make no mistake, ‘Gleason’ is an incredibly difficult film to watch. There are raw and real emotions on display that can be too much to bear. However, it’s still a rather amazing piece of work. This personalized account of ALS and the physical and emotional strains it causes is astounding in its all-encompassing honesty. The perseverance of Steve Gleason and everyone around him manages to somehow overcome every obstacle, even if they tend to play out painfully and messily because there’s no guiding hand of a screenplay to control the story.

The documentary may not be for everyone, but for those inclined to try, the viewing experience is powerful and unforgettable like few others. It’s both an important document of a horrible disease and a moving portrait of how those who are strong enough can survive and even thrive. There will likely be better movies to come along before 2016 rounds out, but it’s hard to imagine any will provide such a satisfying cry at the cinema. Plan your attendance and hanky maintenance accordingly.