For Zombies: walk briskly.

For Global Thermonuclear War: Find a nice place near a likely ground zero for instantaneous demolecularization — so as to avoid slow death by radiation sickness & nuclear winter starvation.

For Climate Change: carry a Nomex suit, a rubber raft, and an umbrella.

For aliens: assume Roddenberry was right until proven otherwise. (If Hawking was right, we’re screwed anyway.)

For all else: maintain a peppy, can-do attitude.