Eric Dane spoke out for the first time on his devastating ALS diagnosis, also known as Lou Gehrig's disease or amyotrophic lateral sclerosis.

Dane shares his daughters Billie, 15, and Georgia, 13, with wife Rebecca Gayheart. In April, the actor told PEOPLE exclusively that he'd been diagnosed with the incurable disease. "I have been diagnosed with ALS,” he shared at the time. “I am grateful to have my loving family by my side as we navigate this next chapter.”

Eric Dane sits down with Diane Sawyer on 'Good Morning America' to discuss his ALS diagnosis and how his family — namely once-estranged wife Rebecca Gayheart, and daughters Billie and Georgia — has been his guiding force.