A number of years ago, while on vacation in Costa Rica, my parents were caught in a riptide. It's an incredibly frightening experience. I was on the edge body surfing, and started to feel the pull of the current. I had thought my parents were closer to shore than me, but I turned around and they were caught in the irresistible force.
It was a small, quiet beach with no help to be found. Fortunately, we knew that to escape a riptide you need to swim across the current rather than trying to fight against it - and further down the beach I was able to get out far enough and pull them to safety.
In business, you are swimming in currents as well, and sometimes an impossibly strong one to resist comes along. It could be a competitive change, a new technology. When this current arrives - you have a choice. You can fight it, and likely drown. You can ride the current to wherever it takes you and hope for the best. Or you can set out a perpendicular course and find a new direction.
Unfortunately, like a riptide, if you aren't experienced in the waters, it is quite easy to miss the strength of the current until it is too late. Having the foresight to take the time to see market, demographic, technological forces is a rare skill, like learning to read the currents from the winds, tides and surface conditions.