The seated twist is a great way to keep your lower back from tightening up unnecessarily. If done on a regular basis, it can also help to keep the the piriformis muscle long, preventing potential issues with sciatica.
To do the seated twist, sit on a supportive yet comfortable surface. Sit with your back straight. Take your right leg and cross it over your left leg, so your right foot is outside your left knee and your left foot is tucked under your buttocks. Take a deep breath in, then let it out as you twist your upper body to the right. You can either hold your right knee with your left hand, gently pulling the leg toward yourself, or, if you’re comfortable, you can place your left elbow on the outside of your right knee.