Attendees of film-festival and film-school screenings frequently endure nonfiction portraits of senior citizens whose lives are assumed to have been sufficiently memorable to warrant a movie’s worth of celebration. But “Hats Off,” a new film about the nonagenarian actress and model Mimi Weddell, which opens Friday at Quad Cinemas, is much more than a loving tribute to grandma or that nice old lady down the hall.

Lean, lucid, focused, and dismissive, if not outright scornful of that which would impede her progress, Ms. Weddell maintains a level of commitment to her health and career that is, frankly, rare in anyone of any age. “I find if people walk slowly in front of me,” Ms. Weddell says early in “Hats Off,” “I want to kick them.” Her charismatic blend of pragmatic determination, scrupulously maintained poise, and aspirational self-absorption is a tough combination to ignore. So much so that the intimate portraiture of “Hats Off” is as much intimidating as inspirational.

“Rise Above It,” says a motto written on the kitchen floor of the Upper East Side apartment Ms. Weddell shares with her grown daughter, son, and young grandchild. Given Ms. Weddell’s gift for gracefully authoritative endurance, one is tempted to sit up straight and ask, “How high?” Propelled by a lifelong restlessness and widowed in her 60s, Ms. Weddell has devoted the last 28 of her 93 years to hustling around Manhattan to open-call auditions and go-sees in order to book work as an actress, print model, or extra. Appropriately, we follow her as she reads for roles, poses for headshots, and dodges the varied humiliations of making a living in front of the camera.

“I rarely get calls for little old ladies,” a casting director, Donna DeSeta, says, “because that’s not what the world’s about anymore.” It’s not really what Ms. Weddell is about, either. Physically strong, strikingly featured, and sharp as a tack, the Mimi on view at home or at work in “Hats Off” is a considerably more evolved creature than the doddering society ladies and bloodthirsty immortals she is shown portraying in film clips. A scene in which Ms. Weddell listens to the complaints of a fellow elderly player whose osteoporosis cost him inches in height and, therefore, his regular bookings playing Abraham Lincoln, is a particularly unblinking view of the undemocratic physical deprivation of age and show business’s equally heartless human commerce.

“Hats Off” assays its unique subject via an equally sanguine first-person recap of Ms. Weddell’s life story and an assessment of her current crusade to “go the sacred mile” until time runs out. Much of the film’s sturdy presentational ease comes from the affectionate yet distanced testimony of Ms. Weddell’s somewhat more traditionally minded children. “Thinness is what she perceives as the Holy Grail,” says Ms. Weddell’s son, Tom, who lives with his mother, sister, and niece in a cheek-by-jowl housing share that would be equally familiar to urban-dwelling Soviets of the 1960s or to modern-day Williamsburg hipsters. Mr. Weddell and his sister’s physical contrasts to their scrupulously gaunt and groomed mother, and their offhand observations about aging while locked into hand-to-mouth bohemia, offer their own lessons in accepting the limits and probing the frontiers of family bonds.