This realisation only comes after he collapses in his trailer. Woodroof, who lives for seven years following the initial prognosis, beats the odds by doing what he does best: hustling.
He pays a staff member at the hospital to steal the drugs he needs to stay alive before heading to Mexico for more medication.
To fund his own treatment he sets up a centre, the Dallas Buyers Club, for non-approved treatments for HIV- positive patients.
Soon hundreds of people are lining up outside his door.
Over time his homophobic views dissipate as his old friends desert him. He also becomes an unlikely champion for the rights of people who have contracted the disease and takes the US Food and Drug Administration to court over its restrictive practices.
The Dallas Buyers Club is a favourite for the Oscars and it is easy to see why. Besides the strength of McConaughey's performance, the film succeeds because it finds humour in the darkest of places.
Watch the trailer here: