Michael J. Fox says his part in the hit TV show "Shrinking" wasn't just a small little acting gig ... but something much more.

Photographers caught up with the movie and TV star at LAX Saturday ... and he was asked what it was like playing Jerry on the show -- a man with Parkinson's disease, just like himself.

Take a listen for yourself ... Michael says this part was more than just a TV role to him -- though he also added it's nice to go to set and do the work.

Fox was also asked about his legacy ... to which he responded he's not worried what people think about him after he's dead.

MJF dove into who inspires him, too ... especially since he's an inspiration to so many -- and, he points to Freddie Roach, a well-known boxing trainer who also has Parkinson's.

Basically, don't try to shrink the importance of this role, Michael says ... it's an important one.