Arnold Schwarzenegger Details Comeback Story After Open Heart Surgery

Arnold Schwarzenegger is chronicling his comeback after open heart surgery in his own words -- while also giving folks a peek at how he did it ... with never-before-seen footage.

The movie star and former bodybuilder blasted out a new newsletter item to members of his health and fitness group, Arnold's Pump Club ... which has some Monday Motivation to get them active and on their feet. For today's catalyst, he shared a very personal story.

He gets into the 2018 medical scare that almost claimed his life. You'll recall, AS was supposed to go into a routine, non-invasive procedure at the time ... but quickly turned much more serious after something went wrong and required full-blown open heart surgery.

Somehow, Arnold was able to recuperate from that procedure in record time -- as he describes in this new video of his, he had a movie to shoot -- and we're getting a chance to see how he went about doing it for the very first time on camera. It's quite something.

As Arnold himself explains ... there were a few things he needed to ensure he left the hospital -- and it all started with a clear vision and a plan of action, which started with him showing he could walk on his own two feet. With the help of friends, Arnold did just that.

We'll let him explain the rest, but essentially ... Arnold's trying to spark some inspiration into anyone who needs motivation to turn their life around and to bring about new lifestyle.

It's pretty inspirational -- as is just about everything the guy does -- and it's also vulnerable.