Hindquarter-in can only arise from a perfect shoulder in. This last exercise should therefore first be comfortable to the horse, before teaching the hindquarter-in.
Hindquarter-in is first trained in hand before riding.
The first day:
Some months later:
As preparation, a small circle can be done to get the required lateral bending. In first instance, a few steps should be enough and when the horse gets stronger this can be built up towards an entire long side of the arena.