Because I was able to submerge myself into the character, I didn't have to go back and forth. You don't have to work hard to bring emotions. It all just comes naturally, you're there living it.
For me everything in the film was gradually building, becoming more emotional, so it helped. At the end of it all I was emotionally drained. At that point I took Rose's view, that this has to happen, there's nothing I can do about it.
It was a huge shock. I've never had hair that short in my life! I think the rest of the cast and crew were mourning my haircut more than I was! But after a while, I felt liberated, I learned to embrace it.