Yet, 10 years ago this week, she was fighting for life after a mystery virus destroyed her heart.
Pictures of Sally lying unconscious on a ventilator in the Freeman Hospital, Newcastle, made the front pages of newspapers across the country, as her family launched a nationwide appeal to find a donor.
After an agonising 10-day wait, a donor was found and Sally's life was saved.
Speaking on the anniversary of her transplant, the 16-year-old has called for organs to be automatically donated – unless people opt out of the scheme.
At the moment, the law requires people to join the NHS's Organ Donor Register.
"My life was saved because someone was kind enough to register," Sally said. "But there are many, many more people whose lives could also be saved if more people registered.
"I know this is hard for many families and the scheme would need carefully thinking through to avoid potential problems, but people have to consider how they would feel if it was their son or daughter, mother or father who desperately needed a transplant."
Sally lives with her father Jon, 46, mother Bridget, 46, and brothers Joe, 15 and Charlie, 13, in Kirkby Malham in the Yorkshire Dales.
But her family's world was turned upside down in 2000 when Sally was hit by a mystery virus.
Mrs Slater, a college lecturer, said: "One night she was sick but we weren't worried. We just thought it was just something that happened to kids.
"She was very listless and lethargic, which is unlike her because she's normally such a bright and bubbly girl."
The illness lasted a week and Sally was taken to see the doctor, who referred her to Airedale Hospital, near Bradford, for tests. She collapsed in the car park.
Tests later showed she had cardiomyopathy, a condition caused by a virus which was destroying her heart. Her condition deteriorated and she had to be transferred to the Freeman, which is the North of England's leading hospital for transplant surgery.
Doctors told the couple their daughter was dying and the only chance of saving her was a transplant.
Mr Slater, a financial planner, did an interview on BBC Radio Newcastle and the family was besieged by the nation's media as their painful story captured the hearts and minds of families around the UK.
Then, on the evening of March 31, the couple received a call from the hospital saying they had found a donor who was a suitable match.
The transplant took place the next day, in an operation lasting 10 hours.
Sally has no memories of the time around the transplant.
"I've never met the donor's family but I know I owe my life to them."
Years on and she still has to take eight tablets a day and has to travel to Newcastle four times a year for medical tests.
But she can enjoy life to the full and loves skiing, netball, running, dancing, singing and acting. Sally joked: "The only sport I'm not allowed to play is rugby – and I wouldn't want to play that anyway !"
The teenager, who is studying for 11 GCSEs, plans to take five A-levels before studying English at university. In the meantime, she plans to celebrate the anniversary of her life-saving operation at a party with friends.
She said: "They all know about what happened to me but they just treat me as a normal girl and I don't feel any different."
Meanwhile, the family are supporting the campaign to help find more organ donors so other lives can be saved.