After leaving school with three GCSEs, Alice Cimino thought there was "no point" in pursuing her dream career as a shark scientist.
Now, she is about to start a PhD after finishing a degree in marine biology.
As thousands of pupils receive their grades, Alice, 35 from Pontypool, Torfaen, said results "don't define where you're going to go".
She said she was "never really good at school" as she always "wanted to be out doing other things".
She was left bedridden at 13 after being diagnosed with chronic fatigue syndrome and needed all her work brought to her.
After getting GCSEs in English language, literature and art, she left school and moved to New York to pursue an acting career, working in bars and clothes shops to support herself.
"But all of the time, whilst this was going on, I had this huge passion and love for sharks that started when I was a child.
"I always thought in the back of my mind 'I want to be a marine biologist', but I didn't have any qualifications to do it. So I thought I might as well just continue trying to make it as an actress."
However, after her dad died when she was 30, Alice decided to follow her lifelong dream.
She was living in Georgia and asked a university there what she could do to achieve it.
"They said because I counted as a mature student, they wanted to use someone as a guinea pig and see how I did in doing a college degree even though I had no educational background'."
After her first year studying marine biology at the University of West Georgia, Alice moved back to Wales to complete the second and third years of her degree at Swansea University - with her next step being a PhD.
"I've gone from being an actress to becoming a shark scientist in the space of 15 years," she said.
"When I was in America I started my own organisation focusing on the awareness and conservation of sharks.
"Then I started at Swansea University, and I wanted to come up with ways of testing shark meat in Majorca for a harmful toxin.
"I had no idea that I was going to actually end up doing what I wanted to do deep down all along."
During her career change, Alice met her partner Dan Abbott, 37, an underwater shark photographer.
The pair run shark snorkelling trips from Milford Haven, Pembrokeshire.
Alice provides information about the science and conservation of sharks, while Dan tells snorkelers about cameras and shark behaviour.
Dan also did not achieve the grades he wanted, scuppering his plans to go to sixth form.
After leaving school, Dan worked as a sound engineer, a drummer, tried a music degree and worked in a call centre before finding his passion in his mid-20s, which has eventually taken him around the world.
"I didn't see my first shark until I was 26," he said.
"So you've got plenty of time to find the passion that you never knew you had, and change your life completely. Your GCSEs and A-levels don't define your future.
"If someone had said to me when I got my GCSEs that this isn't the end of your future, I would have really needed to hear that, because that is definitely the feeling you get.
"It's not the end of the line. It's just the beginning."
Alice added if someone had told her at 16 she would be where she is today, she "would have laughed".
"Just keep going, no matter what. It's going to be OK."
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