The 31-year-old singer -- who is gearing up for another season as a coach on NBC's singing competition The Voice
-- admits she faced major challenges in 2011. "That was a rough year," she tells the magazine
. "Between my divorce and the other things I went through, a lot happened. It's hard for anyone to go through that in public. But when you're a celebrity and under a microscope, it's 58 million times harder. I grew an even thicker skin after that hard year."