The pads on Push are made for expression, and respond to velocity (how hard you initially hit the pad), as well as aftertouch (how much pressure you apply in keeping the pad pressed). Aftertouch can me mapped to a variety of controls - open up a filter by pressing harder, or let in more reverb with a softer touch.

Expanding upon this, Certified Trainer Isaac Cotec aka Subaqueous has built two Max for Live devices for working with aftertouch on Push. Set a threshold for which level of pressure you'd like to have aftertouch kick in, or delay the onset and release of the control. Learn more in the video below: