The two-time Olympic gold medallist made a tearful call in January to parents Robert and Monique, who were spending the winter in Florida. A run of injuries and three surgeries in two years had Vaillancourt contemplating retirement.
The 27-year-old from Sherbrooke, Que., had just started skating and training again following her most recent surgery in November for a sports hernia. She was sore and her progress felt like one step up and two steps back.
"I called my dad and said, 'You know what? I think this is it.' I was crying," Vaillancourt says. "My dad said, 'Sarah, give yourself two weeks and see because you don't want to have any regrets.'
"I gave myself two more weeks and I pushed it hard. I was going to either break or keep going. I don't know why but that was my turnaround."
Vaillancourt played her first hockey game in over a year March 1 with the CWHL's Montreal Stars. Given her lack of games over the last two seasons and the stiff competition for jobs on Canada's national team, it's surprising head coach Dan Church named Vaillancourt to his 2013 world championship roster.
She last played for Canada at the 2011 world championship in Zurich. Vaillancourt made this year's world championship team ahead of Vicki Bendus, who helped Canada win a world title last year in Burlington, Vt.
Church gave Vaillancourt latitude because of her game of skill and sandpaper, plus a decade's worth of international experience.
"She's proven her worth in previous Olympics and world championships," Church explains. "She can put the puck in the net, she's a right-handed shot. She can play power play and penalty kill.
"She's got a lot of skill and talent, but she also plays a real tough game. She's very hard to play against. She's the type of player you want on your team. That's a skill set I think is valuable to us and something we're going to need here in Ottawa."
Vaillancourt was involved in both of Canada's third-period goals that sent Tuesday's tournament opener versus the U.S. into a shootout. Canada went on to win it 3-2.
Rebecca Johnston scored on a rebound sequence that started with a Vaillancourt shot from close range. Vaillancourt put the puck on net for a Haley Irwin deflection, but Catherine Ward finished the play for the second goal.
"I had to adapt to the tempo," Vaillancourt said. "It's been a while since I've played in these games. I felt I gained momentum and started throwing my body out there and I think that's what I have to keep doing."
Vaillancourt was already playing on a deteriorating left hip — diagnosed as a torn labrum — when she joined the Canadian team for their centralized season in Calgary in 2009-10.
The five-foot-five 141-pound forward played on it through a 60-game season, intense practices and dryland training in preparation for the 2010 Winter Olympics in Vancouver. Vaillancourt scored three goals and had five assists in five games for Canada en route to Olympic gold.
Compensating for her hip generated a hernia on her right side that required surgery in late 2010. She continued to play through the pain at the 2011 world championship, but the problem was becoming too much to ignore. Vaillancourt had long-overdue hip surgery in January 2012.
"The surgery itself went well, but I played so much on it that much more had to be done during the surgery itself," she recalls. "It took me a very long time to recover from the surgery and from having played on it for so long. I had zero strength in my left leg. It was really bad."
She began skating again last October only to discover she had another hernia on her left side, which would also require surgery.
"The bottom line was it all started from a bad hip," she said. "There was a point when I found out about the last surgery that I had to get, I thought 'You know what? I think this is it for me.'
"I was really missing hockey. I didn't want to end my career because of something that wasn't my decision. It was getting heavy and hectic, psychologically and emotionally. I told myself to forget about Hockey Canada for now and just focus on coming back to play hockey because that's what I love doing.
"What kept me going was my passion for the game."
Vaillancourt's presence on the world championship roster indicates she's likely to get an invitation to try out for Canada's 2014 Olympic team and be a three-time Olympian.
"They showed they believed in me and what I can bring to the team on and off the ice," she said. "It's hard to get back into it and feel like you are yourself. I can count on two hands how many games I've played this season. It's kind of tough psychologically.
"Good thing this is a team sport and I have a lot of amazing teammates that have been supporting me. I feel like I'm gaining confidence every day."