Grab cans or jars, something with weight to it, for each hand. First try side bends, taking the weight down the side of the leg, leaning sideways in the same direction. Stand tall and go to the other side. You will feel your obliques, which are the abdominal muscles on the sides of your body.
Once you feel good about those, add a bicep curl as you lean to one side. Think about your elbow glued at your waist, curling your weight up as you bring your body down to the side to meet it. And then stand up tall and repeat on the other side, making sure your abdominals are tense like a fist at the center. Do as many as you can for 60 seconds.