To have a complete midsection, both functionally and visually speaking, you need to build resiliency. To do that, my tool of choice is loaded carries. My two favorites are the conventional farmer's walk and the Zercher carry using a strongman log, shown here.
Walk 30-40 yards, but it's good to occasionally do longer distances when endurance is the goal. Do either farmer's walks or Zercher carries once a week, year-round.