Fitness: Some exercises can be done quickly (Image: Octopus/Krissy Cela) "Core engaged, push down towards the ground, bending your elbows and keeping your body in a straight line. Push back up through your hands and core in a straight line." Russian twists "Sit on the floor, bending your knees and balancing on your heels (you can lift your feet up if you can balance)," Krissy explained. "Lean back to a 45-degree angle, core engaged, back straight, until you feel tension in your core. "Take your hands from left to right, twisting your abdomen, aiming to touch the floor. You can hold a dumbbell or some resistance, like a water bottle, if you have this at home."