Celine Dion is focusing on her family and the future as she continues to live with a health challenge.The legendary entertainer marked International Stiff Person Syndrome Awareness Day on March 15 with an Instagram post in which she addressed her autoimmune disorder, saying it "has been one of the hardest experiences of my life."Dion added that she remains "determined to one day get back onto the stage and to live as normal of a life as possible."A photo of Dion and her three sons – René-Charles and twins Nelson and Eddy – accompanied her heartfelt message.Dion shared her three children with her late husband René Angélil, who died in 2016.Stiff person syndrome (SPS) is a rare neurological condition that causes spasms and muscle rigidity. It is characterized by muscle rigidity and spasms, heightened sensitivity to stimuli such as sound and lights, and emotional distress that can cause muscle spasms, according to the National Institute of Neurological Disorders and Stroke.Dion first shared her diagnosis in 2022. She has since stopped touring and performing live.A forthcoming documentary on the "My Heart Will Go On" singer set to stream on Prime Video will document her journey back to the stage.On Friday, Dion wrote in her caption that is sending her "encouragement and support to all those around the world that have been affected by SPS.""I want you to know you can do it! We can do it!" she concluded.