Pushing is a different kind of stunt, when you are trying to outdo yourself rather than another. Pushing is used to temporarily improve an attribute past normal limits. Say you have to lift a 300 kg sever lid, which normally takes a Strength of 11, but you only have a Strength of 8. How is this possible?
Simple, make a push roll, and for every five points you exceeded the difficulty, add one to your attribute for this stunt. If there are no distractions, the difficulty is generally zero, but distractions can severely increase this.
Generally, pushing physical attributes uses Martial Arts, but sometimes other skills, or even Dodge can be used, at the GMs whim. Pushing vehicles is done with Drive.
If you still fail your push, you cal elect to overstrain yourself and take Wound Points equal to the difference between what you did roll and what you had to roll in order to succeed anyway.
Other uses of pushing include racing (Move) and holding your breath (Constitution).