Keep Calm and Carry On!
The panic button is always way too close. So, this advice, intended for a WWII audience, is always relevant. Panic is hardly ever the right choice.
Oh, and why this is popular now? Because the post 9/11 Aughts were chock full of panic and fear. Keeping a stiff upper lip and carrying on may not always be a good idea (WWI military strategy), but in general, it is way better than the alternative. Oh, and this has nothing to do with living with a teenager. Really.