Just 2 days after the 56-year-old UFC Hall of Famer suffered a heart attack and underwent an emergency procedure ... Couture walked out of Cedars Sinai under his own power.

Couture, clutching an adorable oversized stuffed animal, was surrounded by his family and friends as he walked home Friday ... and told TMZ Sports all about the experience.

"Feeling good, way better obviously," Couture said ... admitting the health scare was a reality check about mortality.

"At some level, you think you're invincible and then you find out you're not."

The good news, Couture says doctors have identified the problem and he'll be following up with specialists to make sure this never happens again!!!

Couture says he's already itching to get back in the gym and resume training with his MMA pals ... but knows he should take it slow. Good luck stopping this man.

Oh, and he's already planning to get back to work in Hollywood -- telling TMZ Sports he's got a shoot for a new movie with Michael Jai White on Tuesday and he ain't missing it!!!

There's more ... Couture says he was overwhelmed by the outpouring of support from close friends and old rivals ... including Chuck Liddell and Tito Ortiz, who both reached out.