Dwayne ‘The Rock’ Johnson wanted to be in the “best shape of his life” for ‘Black Adam.’ The 50-year-old actor stars in the upcoming superhero movie and explained that because it was the “most important” role of his career to date, he felt compelled to change his diet and maintain his peak physique during the four-month shoot. He said: “This was it for me. This is the most important role of my entire career that I’ve been so lucky and blessed so I wanted to be in the best shape of my life. I felt like ‘Black Adam’ commanded that. I changed my diet around, my training. The challenge is when you…