Let’s not get caught off guard by an Earth-killing asteroid. As Dylan Thomas said: “Do not go gentle into that good night, …rage against the dying of the light.”
That is the mission of NASA. If you are reading this, chances are that Asteroid 2012 TC4 whizzed by today at 30,000 miles per hour—closely monitored by a network of observatories. Check out the details at this NASA website. They take asteroid defense very seriously. Their defense plans for redirecting asteroids will be tested out in 2022 on a double asteroid Didymos B as explained here.
Keep in mind that asteroid 1950DA, about three-quarters a mile wide—big enough to destroy our planet, has a 0.1% chance of hitting the earth 2818. In case NASA does not succeed in their defense efforts, start digging now and you might get hunkered down enough to survive for a short while after that.