Well to be a bit err blunt, an exaggerated seat push would be like trying to umm, well you know that dance where guys shake their booty and thrust forwards, that kind of thing with your tail and seat bone as if you are pushing the back of the horse on forwards. This is the moment in lessons when my students giggle like mad as I show them lol, but they get the meaning and then after a few tries the deep seat contact feels more natural and the horse responds by increasing their impulsion and rounding into the canter.
<< exit one red faced Cassie lol