How long does it take for good posture to feel natural?

I’ve always been focused on trying to improve more minor details like my eyebrows, lip colours, and eye makeup, until I recently realizing that I should probably start with something that people can notice from further away.

So I’ve been wanting to improve my posture and have been very conscious of keeping my head held high and my back straight while also trying different workouts to improve my core.

My question is at what point does all of this start to feel natural?? As soon as I forget about it, I realize that I’m back to slouching and looking like a shrimp