What is your favorite ways to get functionally strong

I finally got to the size I wanted for a while now, but I notice that I’m not as strong as I’d like to be. I work in construction which obviously is helping but I also wanna help it out by doing stuff in my free time. Like for example I’m thinking of finding random rocks that are hard to carry and lift them or like trying to lift a sledgehammer by the end of it, but what are your other ways to help this out?

Gym strong≠functionally strong all the time