Janet Jackson is working hard to guarantee her upcoming tour will be "perfection," a source close to the Jackson family tells ET. The “Rhythm Nation” singer lost a whopping 50 pounds in just a few months after having baby Eissa. On Monday, Miss Jackson showed off her slim post-baby body on Twitter, sharing a pic of herself in rehearsals. Sources says Jackson's been rehearsing "almost 15, 16 hours" a day in preparation for her State of the World tour, which kicks off in Lafayette, Louisiana, on Sept. 7.