Arnold Schwarzenegger is continuing to recover after a planned medical procedure last week turned into surprise open heart surgery. Now, the actor is officially "back" on Twitter -- and sharing his gratitude.

The "Terminator" star tweeted out a modified version of his character's signature catchphrase on Monday, marking his first public comments since his surgery. As the actor explained it, he "went to sleep expecting to wake up with a small incision and woke up with a big one."

But while his body may have taken more of a beating than he bargained for, Schwarzengger said he was "thankful" to make it out alive at all. He also added his thanks to his medical team, as well as fans who sent well wishes.

On Friday, the former governor of California underwent what was to be a routine heart valve replacement surgery, only for doctors to discover a problem mid-procedure that required open heart surgery instead. The valve, which was first installed in 1997 to repair a congenital heart defect, was later successfully replaced.

Considering how soon he's been able to joke about it (Schwarzenegger also quipped "I'm back!" after he first woke up from surgery), it looks like the actor's recovery is going well so far. May it continue.

[via: Arnold Schwarzenegger/Twitter]