Singer and producer David Osmond inherited his love of music from his famous father, Alan Osmond. But he also shares with his dad the diagnosis of multiple sclerosis (MS), an unpredictable and often debilitating disease of the central nervous system. MS often causes symptoms such as fatigue, difficulty walking, numbness or tingling, weakness, vision problems and pain, according to the National Multiple Sclerosis Society. “I remember as a kid when my dad told us that he had something called MS,” David tells Yahoo Lifestyle. “We saw him start to decline physically.” David says his father started tripping and falling onstage as his disease progressed. "It was hard to see," he says. MS has many causes, including infectious disease, immunologic factors, environmental factors and genetics, according to the National MS Society. Still, David says, “the thought never really crossed my mind that I might have MS or that it might be genetic.” He first started developing symptoms at age 26 and was diagnosed with the disease later that year. “I took my shoes off and I turned to my girlfriend. I said, ‘My feet feel like they’re being run over by a steamroller,’” David recalls. “Within a few weeks, that crushing feeling progressed up my legs. It was all the way up to my chest within a few months.” Soon, David was in a wheelchair, which he sat in even as he proposed to his now-wife. “She said, ‘Yes, in sickness and in health,’” David says. “Her strength has helped me so much.” David eventually was able to walk again and is currently touring with his famous aunt, Marie Osmond, and uncles Merrill and Jay, but he’s not symptom-free. “I’ll be honest, right now I’m in a massive amount of pain,” he shares. “And it’s all over the place, but I don’t dare complain about it.” Getting his diagnosis made David worry about his future, and at the time, he wondered whether he would ever be able to walk again. “I hope to encourage people who are going through a struggle just to know that you’re not alone,” he says. “There are people who know how you feel that are behind you and fighting for you. Never give up.”