She explained to the UK edition of OK! magazine: "We need to make mistakes in order to avoid them in the future. I made a lot of mistakes and I've grown into a better person because of it.
"I'm now taking better care of myself. I don't let my schedule determine who I am. I don't fly around the world constantly. I don't work 24/7."
Demi also revealed she has been more careful about who she associates with since she left rehab in January 2011.
She said: "You need to be careful of who you hang out with, people you listen to. They can lead you down the wrong path, they can give you the wrong kind of direction. Try to stay away from the temptation."
Meanwhile, Demi has bonded with fellow 'X Factor' USA judge Britney Spears after stand-in panelist Louis Walsh taught them a funny game.
Louis explained he and his fellow judges on the UK version of the show like to choose a word before auditions and try to use it during their critiques.
After Britney chose the word tiger, the pair were in fits of giggles as they incorporated it into their appraisals with L.A. Reid telling one pop hopeful "he looked like a tiger in his tank," while Demi added "I can see a little tiger action," with Britney chiming that he "was like a big tiger".
A source told Us Weekly: "Every time one of them said the word, they all started giggling like naughty school children."