Fox came out of retirement to star in the series, which features Ford as a therapist who has Parkinson's disease

His presence on set has been “essential,” the “Indiana Jones” actor told Variety in an interview published Wednesday, saying that Fox “gives me both a physical representation of the disease to inform myself with, but more than that, he allows me to believe that Paul could believe that he could be adequate to the challenge.”

Harrison Ford Shares Powerful Words About Michael J. Fox originally appeared on Parade. Harrison Ford is opening up about his admiration for Michael J. Fox.