To mobilise the spine through lateral flexion (Side bend), try Standing Side Reach (this also encourages lengthening and strength in the waist).

Stand in good posture with feet at hip width. Breathe in and raise one arm towards the ear. Breathe out to tilt the spine sideways from head to waist, keeping the pelvis still. (Focus on staying long on both sides of the waist). Breathe in to hold the position and return to the start position on the out breath. Alternate sides for about 4 on each side.

You can also try this sitting on a chair or on the floor.