Marcus Smart discovered the impact of COVID-19 very early in the coronavirus' sweep through the United States.

On March 19, 2020 -- just a week after the NBA shut down due to the virus -- the Boston Celtics guard was diagnosed with COVID-19.

Smart exhibited no symptoms and did his part in the nation's battle against the virus by donating convalescent plasma for research.

Smart learned plenty about COVID-19 in the process, especially after his father contracted the virus a few months ago. As part of NBC Sports' "Headstrong" initiative, Smart spoke about the lessons he learned from his bout with COVID-19, why his decision to donate plasma was a "no-brainer" and the advice he'd give to the American public as it continues to battle the virus.

Check out Smart's story in the video player above.