The 33-year-old actor and filmmaker has revealed that he signed up to join the volunteer program - which provides social and economic development abroad through technical assistance - but withdrew his application after he went into court-ordered rehab in 2017.
Whilst in rehab, Shia wrote his new movie ‘Honey Boy’ - which is based on his own life, and sees a young Shia attempt to reconcile with his father, whom Shia himself plays in the flick - and decided to continue to focus on acting once he left the treatment facility.
He explained during an appearance on ‘Jimmy Kimmel Live!’ on Wednesday (06.11.19): “I thought the acting thing was over and then I signed up to go to the Peace Corps and then went into this rehab facility, was there for two months, had written this thing, plans changed.
“So when I got out, I wasn’t gonna do the Peace Corps no more. So we had a little conversation about it, they were very peaceful about it . . . It’s not like the navy or something like that.”
Shia was encouraged to write the script for ‘Honey Boy’ whilst in rehab, as he was told writing down parts of his life would help him to cope with his Post Traumatic Stress Disorder (PTSD).
And the actor recently revealed his life as a child star - during which time he starred as Louis Stevens in the Disney Channel series 'Even Stevens' when he was 14 - as well as traumatic childhood events including his parents splitting when he was just five, and growing up with an alcoholic father, contributed to his PTSD diagnosis.
Reflecting on his own situation, the 'Transformers' star admitted he feels that if he "had more money, there'd be no fighting" between his parents and that working was an "opportunity to be able to minimise the drama”.
Of his diagnosis, he added: "It was the first time I'd been told I had PSTD.
"I just thought I was an alcoholic, like a true-blue drunk and I needed to deal with that.
"I knew it was an issue but didn't know there was this extra whole other thing that was hindering my ability to have any peace in my life and my ability to deal with people."