By Liz Calvario‍ ‍Original Source: Entertainment TonightSia is celebrating eight years of sobriety.The 42-year-old "Elastic Heart" songstress hit a big milestone on Monday and shared the grand feat with her fans and followers. In a simple tweet, Sia shared a motivational message about fighting the battle against addiction, eight years after she decided to change her life."Eight years sober today. I love you, keep going. You can do it," the singer-songwriter shared on Twitter and Instagram. Fan of the GRAMMY-nominated artist congratulated her, as well as replied with messages of love and...click here to continue reading