Below are four wall exercises that can help flatten lower belly fat faster than sit-ups after 55. Wall PlankBegin by standing tall facing a wall, about arm’s length away from the surface. Wall Plank Shoulder TapsBegin by standing tall facing a wall, about arm’s length away from the surface. Wall-Supported Knee DrivesBegin by standing tall facing a wall, about arm’s length away from the surface. Wall SitsStand tall with your back pressed against a wall.