main.rs

use futures::future::Future;

struct MyStruct {
    msg: String,
}

impl MyStruct {
    fn new(msg: String) -> Self { MyStruct{ msg  } }
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
    let a = MyStruct::new("hello world".to_string());
    tokio::task::spawn(foo(&a)).await?;

    Ok(())
}

fn foo<'a>(ms: &'a MyStruct) -> impl Future<Output=()> + 'a {
    async move {
        println!("{}", &ms.msg);
    }
}