Jeremy Renner prepared for the worst after his snowplow accident.

The Marvel star recalled being in critical condition when he was rushed to the hospital after being run over by a snowplow on New Year's Day. And due to the serious nature of his injuries, he even wrote a final message to for his loved ones in case he didn't make it.

As seen in a preview of Renner's upcoming interview with Diane Sawyer set to air April 6, the 52-year-old tearfully shared, "I'm writing down notes in my phone, last words to my family."

And he credits his nephew Alexander Fries being present when the accident occurred as the reason he survived.

"If I was there on my own, that would have been a horrible way to die," the Mayor of Kingstown actor noted. "And, surely, I would have. Surely. But I wasn't alone. There was my nephew, sweet Alex, and the rest of the calvary came."

According to a Washoe County Sheriff's Office report obtained by E! News, Renner was using a PistenBully to tow a truck that had gotten stuck in the snow on his driveway in Nevada. After he and his nephew moved the truck, Renner drove the machine up the street and turned it around. He then noticed it was starting to slide. 

"The Pistenbully snow groomer began sliding causing Renner to exit the vehicle without setting the emergency brake," the report stated. "Although the Pistenbully had some mechanical issues, it is believed based on our mechanical inspection that the parking brake would keep the Pistenbully from moving forward. When Renner attempted to stop or divert the Pistenbully to avoid injury to Fries, he was pulled under the vehicle by the track and was run over."

As noted in a March 29 preview for his upcoming sit-down with Sawyer, Renner suffered from injuries that included eight ribs broken in fourteen places and a collapsed lung.

Looking back on the pain he endured, Renner noted in that preview clip he was "awake for every moment," and that he would do it again "because it was going right at my nephew."

Two weeks after his hospitalization, Renner confirmed that he was home from the hospital on Jan. 16. Since then, he has continued to share glimpses into his road to recovery on social media.

Most recently, on April 5, Renner reposted a photo of himself working on his recovery, sharing it with an inspiring message: "This pain, Agony, Soreness … Ain't nothing but PROGRESS."