Whilst standing with knees slightly bent, slump forward at the thoracic and lumbar spine whilst flexing the neck by placing the chin on the chest.
Rest the arms on a table or chair. Gently rock backwards onto your heels whilst straightening the knee.
Only rock back until the stretch starts (or the leg begins to shake). There is no need to force the move or hold. We are simply looking at nudging the range.
Release back by bending the knees again and placing the feet flat on the floor.
Repeat 10 times.