Lululemon is thriving in China but struggling in North America.Cheng Xin/Getty ImagesLululemon has seen sales slide in North America, but it's thriving in China.Stiff competition and product mishaps hampered consumer demand for Lululemon in the US and Canada.But in China, changing health habits and a struggling luxury sector are helping to boost sales.China is in its health and wellness era, offering Lululemon a ray of hope as the brand struggles to engage consumers back in the US and Canada, where it was founded.In its most recent earnings release in August, Lululemon reported that same-store sales in North America fell by 3% during the second quarter versus the year before.