Neil Bradbury, from Hednesford, died on November 15, 2015.
Amy Windle, who was Mr Bradbury's girlfriend, said his family and friends have since raised more than £13,000 for charity Cardiac Risk in the Young (CRY), and have also raised £8,000 for four defibrillators to be installed around the town, and are now raising funds for the fifth.
The 37-year-old said: "Neil was fit and healthy, there were no underlying health conditions that we were aware of.
"He had two autopsies and neither found anything, it was put down to natural causes.
"I found the charity CRY, who said there is a minimum of 12 people a week who die aged 14 to 35 of similar causes, and they support families.
"I was supported by them and so we started off raising money for them.
"We held a screening session in 2018 and have raised £13,000 for CRY.
"I have now completed a course to be a bereavement supporter, and we now raise money for AED Donate, a charity which installs defibrillators.
"This one is our fourth and is in Hednesford Park.
"We've had people do sponsored events for us, and we do annual events such as a charity football match and fun day.
"He would have been 40 in March so we're doing a birthday party to raise funds.
"He was really well known around Hednesford."