Always watch for what comes next. Defending a two hand push is near impossible, especially if there is minimal distance between you and the aggressor. What you should be watching for is what comes after the push. Most aggressors use a push as means to set up punches, a tackle, or even draw a weapon. My advice is get your hands up immediately and ready to act accordingly, even if that means throwing the first punch. Be sure to follow for daily self defense tips, techniques, and fight breakdowns.