Traditional apparel retailers are struggling. Teen brands like Abercrombie & Fitch, Aeropostale and American Eagle are downsizing and changing their strategies, while C. Wonder and Wet Seal have shut down locations. The problem? Millennials want more casual clothing.

Yoga apparel brand lululemon has achieved record sales by employing a combination of scarcity marketing, fanatical sales teams and self-help teachings to create a cult-like following.

Women's fitness and wellness is an increasingly sexualised industry, characterised by an obsession with an enhanced physical appearance. But how do real women feel about the sexualisation of wellness? Could the allure of feeling sexy encourage more women to work out?

Yoga products are worth $27 billion annually in the US. And while it's true that the number of people practising yoga – predominantly women – has increased by 20% in recent years, that doesn't explain why sales of yoga wear are up 87%. Are yoga pants set to become the next Levi's 901s?