Harrison Ford -- Leg Injury is Healing Fast ... Famous Trainer Says

Fun fact: Harrison Ford's trainer is the guy who invented Body by Jake ... and he tells us Han Solo is progressing faster than the Millennium Falcon in a Kessel run.

Jake Steinfeld was hanging out in Beverly Hills when he gave us the 411 on Ford's injury.

Turns out Jake and Harrison have been working together since the "Indiana Jones" days ... and they still keep in close contact.