This exercise works your obliques and strengthens your back which helps with maintaining good posture. No equipment is needed unless you want to increase intensity by adding a weight.
Sit on the floor with your knees bent and your feet flat on the ground.
Lean back so your torso is at a 45-degree angle to floor, making sure to keep the spine straight and not rounded.
Place your arms straight out in front of your chest with one hand on top of the other.
Raise your core and slowly rotate round to the right as far as you can, pause then reverse this movement all the way round to the left as far as you can.
To work harder without adding any weights simply lean back a little bit further.