That positive attitude made Ruszczyk, 40, a favorite in her community -- and made her sudden death jolting.
A passionate advocate of nonviolence, she was shot to death Saturday night.
Ruszczyk had called police to report a possible sexual assault near her home, her fiancé, Don Damond, said Monday.
Two police officers responded, and one of them shot her in the abdomen, killing her, according to police and an autopsy released Monday.
Police have not explained how the shooting happened, leaving friends and family demanding answers.
"The death of Justine is a loss to everyone who knew her. She touched so many people with her loving and generous heart," Damond said Monday.
She was living with him at the time of her death and had already adopted his surname professionally.
"Our lives are forever changed as a result of knowing her," Damond said. "She was so kind and so darn funny. She made us all laugh with her great wit and her humor."
Australian Prime Minister Malcolm Turnbull said the killing was shocking, adding that the government wants to know how it occurred.
"Our consul general is supporting the family and we are seeking answers to this," he told Australian Channel 9's "Today" show.
"This is a shocking killing. It is inexplicable. Our hearts go out to her family. I mean, how can a woman out in the street in her pajamas seeking assistance from the police be shot like that? It is a shocking killing."
'Dark night of the soul'
Ruszczyk had lived in the United States since April 2014, said someone who knew her. She had dual citizenship in the United States and in Australia because her father holds US citizenship, the source said.
She quit her career as a veterinary surgeon to become a spiritual healer after losing her mother to cancer and reconsidering her purpose in life, Ruszczyk said in a video recording of a talk she gave July 2 at Minneapolis' Lake Harriet Spiritual Community
, where she worked.
In the video, Ruszczyk said she experienced a "dark night of the soul" on New Year's Day in 2006 while traveling and began to consider the message of a movie she'd seen, "What the Bleep Do We Know?" That film is about "a world where science and spirituality converge," according to a website for the movie.
Ruszczyk said seeing the movie made her wonder, "Maybe our thoughts have a measurable effect on our reality? Maybe the way we think and feel can not only affect our reality but perhaps create it?"
She began to explore alternative therapies, mind-body medicine and studies in Eastern philosophies, consciousness and quantum physics, she wrote on her professional web page
In her business, she offered personal development and leadership training for individuals, groups and businesses.
"She was a gifted speaker, meditation leader, teacher and transformation coach," said Nancy Coune, an administrator at Lake Harriet Spiritual Community, where Ruszczyk was supposed to give a talk Tuesday. "Her message is of love and peace and nonviolence."
Her sense of humor remembered
Ruszczyk grew up in the Sydney suburb of Freshwater and attended nearby Manly High School and later the University of Sydney. She reviewed books for a Sydney neighborhood newspaper, the Manly Daily, the Australian Daily Telegraph reported
A former colleague from the newspaper, reporter Rod Bennett, recalled her warmth and humor.
"We became good friends and often shared a laugh," Bennett told the Telegraph. "She had a terrific sense of humor and we immediately hit it off as mates. This has shocked me. I will miss her."
Julia Reed, a longtime neighbor and family friend of Ruszczyk's, spoke to Australian media on behalf of the slain woman's family.
"She undoubtedly will be very missed by the family," she said, her voice cracking with emotion. "She was treasured and loved, and we will really miss her."
Bridging spirituality and science
speaking from England, told CNN's "New Day" she befriended Ruszczyk in Sydney years ago as she transitioned away from the veterinary profession.
"It was almost as if when we met that she made a decision to fully commit to her purpose," Kinnie said. "And that was to bridge science and spirituality. ... She had an incredible love of animals, and she was very clever and very intelligent with regards to science, which I feel ... almost paved the way to bridge, you know, her spirituality."
Ruszczyk was equally loved in her adopted hometown of Minneapolis as well as respected professionally. Always an animal lover, Ruszczyk also volunteered at a local dog shelter, Secondhand Hounds, colleagues told CNN.
"Justine has an energy and care that allowed me to feel safe from the moment I walked in," says a testimonial on her website, attributed to a wellness consultant named Jo Grabyn. "Working with Justine changed my life in ways I never thought possible."
Anger over her death
Her father gave an emotional plea for justice Tuesday.
"Justine, our daughter was so special to us and to so many others," John Ruszczyk told journalists in Australia
, reading from a prepared statement.
"We went down to (Freshwater) beach this morning and saw the blackness change to light.
"Justine was a beacon to all of us. We only ask that the light of justice shine down on the circumstances of her death."
Soon after her death, Ruszczyk's stepson, Zach Damond, took to social media
and expressed anger at the man who killed his "best friend."
"My mom is dead because a police officer shot her for reasons I don't know, and I demand answers," he said in a video posted to Facebook, wiping tears from his eyes.
'A beautiful light'
On Sunday, members of Women's March Minnesota honored Ruszczyk in a vigil
near the scene of her death. They wrote tributes in chalk across the pavement, while lighting candles and placing flowers at a makeshift memorial. One sign read: "Why did you shoot and kill our neighbor and friend?"
"This woman was a beautiful light. She was a healer, she was loved. ... She should still be here," one woman named Bethany said to applause.
"This should not have happened. ... That could've been me, that could've been you, that could've been you, that could've been any of us," she said.