The thing is, depression is a continuum and it is like going down the proverbial rabbit hole.
At first, you get discouraged and sad. Those are normal human emotions; everyone has them. But then you stay there and it turns into mild depression. At this point, hopefully, you haven’t created an emotional habit yet, and you can shake it off.
But if you don’t, your mind and your body start to get used to being in this state, making it harder to shake off. And the longer and longer it goes on, the farther you go down the rabbit hole, and the more and more effort it will take to get out of this state and find a way back to the surface.
You may even get to a point where you need some professional help to guide you back to the surface.
And for someone in the rabbit hole, getting guidance to the surface feels like you’re in the rabbit hole by yourself, in the dark, with someone on the surface talking to you via radio trying to tell you which way to go. So getting out isn’t always that straightforward, at least while you are stuck in it.
So, depression is something that you can indeed shake off in the beginning before you get too far down the rabbit hole. But it is also something you might need a guide back to the surface, because even if you “shake it off” you still may be lost in the rabbit hole.
So both perspectives are right; it just depends on where you are on the depression continuum and how lost you are in the rabbit hole.
If you can find your way back to the surface, you can shake it off. If you are lost in the rabbit hole, shaking it off is not enough. You have to find a way out too.