The A-list actor and former California Governor delivered an epic address via ATTN to all the grads who couldn't attend their own in-person ceremonies -- and his takeaway message was very clear, and at times ... brutally honest. Have yourself a vision, damn it.

Arnold said that while the pandemic might seem like the biggest obstacle to overcome right now, he assured the grads that more would come throughout their life ... adding that having a clear and attainable goal in mind would undoubtedly help them move past them.

He gave a very personal example that hits home for him -- his 2018 emergency heart surgery that could've killed him, according to AS. He recounts how, at first, he thought he was going to have a simple, non-invasive procedure done to replace a heart valve -- but was fighting for his health back after things went left and they had to open him up.

During the story, Arnold shows off never-before-seen footage of him in the hospital at the time, and the rehab he had to endure to get back to peak condition ... and to get back to the new 'Terminator' set he was supposed to be on starting August 1. Because of his vision, Arnold says he was able to get there -- and suggested grads strive or the same clarity as they go forward, sometimes in pretty blunt terms too. This speech ain't for TV.

It's an 11-minute clip here, but it's very much so worth the full watch. BTW, he also takes a shot at Trump toward the end to highlight that it's not about the diploma in the end.