Legendary NFL quarterback Dan Marino, 64, reveals health issue he's been battling for 18 years

Known to many as fatty liver disease, Metabolic Dysfunction Associated Steatosis Hepatitis (MASH), impacts 1 in 20 Americans, or about 15 million citizens.

Legendary Miami Dolphins quarterback Dan Marino has quietly lived with the disease since 2007, but is now speaking out about the condition on behalf of pharma giant, Novo Nordisk.

'Novo Nordisk is a company that I wanted to get involved with because they're trying to make a difference,' the Hall of Famer told Fox News on Monday. 'It's manageable with early detection. So, go to your doctor and get your normal checkups like you always do.'

The company launched what Marino referred to as an 'awareness campaign' about MASH one month after the FDA approved its weight-loss drug, Wegovy, to treat the disease in adults with moderate-to-advanced liver fibrosis.

'I kind of let my diet go … that's really where [MASH] kind of came about,' he told People.com of his 2007 diagnosis.

'The doctors right away said that can be reversible, it can be taken care of, but, mainly for me, they were saying, like, 'You gotta work out. You got to lose weight.'

Predictably, Marino's doctors recommended diet and exercise for the issue, which can lead to liver damage, increased risk of heart attack or stroke and even atherosclerosis, which is the hardening of the heart's arteries.

'It's the exercise, riding bike, walking, and diet, and then getting back to just being consistent — waking up and making sure you gotta do something every day,' Marino told People.

Marino still works out with former Dolphins teammate Terry Kirby and regularly goes biking with his wife, Claire.

The Novo Nordisk campaign, titled 'Unordinary stories,' also includes testimonials from WNBA legend Sheryl Swoopes as well as others suffering from issues with MASH, diabetes, and obesity.

'If you get diagnosed with fatty liver and MASH, doing the things you need to do, like I talked about — diet, working out — and staying consistent with it, that's what our message really is,' Marino told People.

Marino's compensation for the campaign has not been revealed publicly.  

A 17-year NFL veteran considered by many to be the greatest passer in league history, Marino still ranks seventh all-time in passing touchdowns (420), ninth in yardage (61,361) and 10th in competitions (4,967).

The Pittsburgh native and Pitt Panthers legend was inducted into the Pro Football Hall of Fame in 2005.