Both examples are extracted from The Guardian newspaper.
Clark points out that Coca-Cola is at least promoting its Coca-Cola Zero at the Rugby World Cup later this year rather than its full sugar Coca-Cola as it did with its London Olympics sponsorship, but stresses that a healthy lifestyle “is about what goes into your body and the effects that can have, not just running around a bit to burn off a few calories”.
If I wrote the above paragraph, I would write "healthy lifestyles" are bla bla bla. This is because the paragraph is generally talking about "lifestyle" which is a countable noun. The following example was extracted as well from the Guardian:
Other initiatives include equal attention to mental and physical health and partnering with day-care facilities, schools, workplaces and others to embed healthy lifestyles.
What I missed here?