I think the meaning is clearly described in the subtitle, but I always saw it as something kind of opposite of that until I read that. It reminded me of when something awful happens, like the death of a loved one, or a particularly traumatic break-up. Just as you are moving on and getting back to the status quo - a la mundane tasks - all of a sudden the full weight of what happened ca hit you like a freight train. Then you find yourself reliving that terrible experience in your mind all over again. Suddenly you feel the entire weight of what happened. You go through it, get back on your feet, and then the cycle starts over again. But either way, it's the enormity of a life-change hitting you as soon as you let your guard down.
I think the meaning is clearly described in the subtitle, but I always saw it as something kind of opposite of that until I read that. It reminded me of when something awful happens, like the death of a loved one, or a particularly traumatic break-up. Just as you are moving on and getting back to the status quo - a la mundane tasks - all of a sudden the full weight of what happened ca hit you like a freight train. Then you find yourself reliving that terrible experience in your mind all over again. Suddenly you feel the entire weight of what happened. You go through it, get back on your feet, and then the cycle starts over again. But either way, it's the enormity of a life-change hitting you as soon as you let your guard down.