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PE teacher Vicki Randall turned to coaching after being forced to give up playing netball and football because of injury.
The 29-year-old has encouraged more than 200 girls to play sport every week.
"I say quite often to them I don't care about the score, I just want them to enjoy it," Vicki said.
"I know that they appreciate everything that I do and at the end of the sessions they'll all say thank you."
Vicki set up Cwmbran Youth netball club in 2009 with just five girls, which has now grown to 14 teams. Three players have recently been selected for Wales' under 17 squad. She also organises a weekly 'netball tots' club for children aged between one and five.
She also runs Risca Netball Club, managing all five of their teams in the South East Wales League.
Vicki also set up Cwmbran Celtic Ladies football team in 2012, guiding them to promotion to the Welsh Premier league two years later and also started a reserve team to encourage women to take up the sport.
She typically spends four evenings a week coaching sport after work, often more than one session per evening. At weekends, she spends most Saturdays organising netball matches and tournaments, before devoting up to seven hours on a Sunday to her football teams.
Despite undergoing nine operations on her knee she has continued to coach, sometimes on crutches or in a wheelchair.
Vicki was nominated by Ann Daley from Pontypool whose daughter plays netball with Cwmbran Youth.
"Vicki has given so much to so many, volunteering all her free time," Ann Daley said.
"She has had a massive impact in raising levels of participation in sport for girls and women in South East Wales. Vicki really is an Unsung Hero."
Vicki's achievement will be recognised at the Wales Sport Awards 2016 on Monday, 5 December at Hoddinott Hall in Cardiff,
She will share the stage with the night's other big winners including Coach of the Year, Team of the Year and the prestigious BBC Wales Sports Personality of the Year.
The Wales Sport Awards 2016 will be broadcast live from 19.30 GMT on Monday, 5 December at the BBC Wales Sport website and also on BBC iPlayer and the Red Button. The event will also be live on BBC Radio Wales.
The Wales Sport Awards is an event, organised in partnership by BBC Wales and Sport Wales. It aims to recognise the best achievements at elite and community level in Welsh sport.
Watch BBC Wales Today at 18:30 GMT on BBC One Wales this evening to see the moment presenter Claire Summers surprises Vicki with her Unsung Hero award.

The seven-month-old died at a house on Melrosegate, York, on 3 November.
The death prompted a Sheffield-based bed company to issue a product warning. A joint investigation between police and Trading Standards is under way.
North Yorkshire Police said the 35-year-old man from Rotherham, South Yorkshire, was assisting with the inquiry.
No cause of death for the infant has been confirmed.
Read more about this and other stories from across Yorkshire
Police have issued a safety warning to customers of Playtime Beds Ltd.
"If they have ever had any safety concerns or a child has suffered an injury as a result of the design of the bed, then please contact us," a spokesman said.
Playtime Beds Ltd of Sheffield, which has ceased trading, is working with Trading Standards over safety concerns about products it had produced since 2011.
It issued a product warning in December which advised that risks to children could include asphyxiation or strangulation, falling, entrapment or crushing.
The company produced a range of bespoke children's cots, twin beds, bunk beds, cabin beds, high sleeper beds and triple and quadruple beds.
It added parents should stop using the beds immediately and to contact Trading Standards.
A volunteer netball and football coach from Cwmbran has been named as BBC Wales Sport's Unsung Hero for 2016.
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A man has been interviewed under caution by police investigating the sudden death of a baby.