Ready for some Friday R&R? Catch up on the latest and Greatist in fitness, health, and happiness with our weekly roundup of our most popular articles this week:

Meet Our Expert: Sherry Pagoto

Meet Sherry Pagoto— obesity researcher, avid runner, mother, and this week’s Greatist Expert of the Week!

Superfood: Pistachios

These little green nuts may be good for more than a fun party snack— they’re also a naturally cholesterol and sodium-free snack high in fiber and protein. Find out what else makes pistachios this week’s Greatist superfood.

What’s Actually in Tap Water?

The water from your faucet may have more on tap than pure, hydrating goodness. Studies show that contaminants like lead, bacteria, and nitrates regularly make their way into tap water supplies— but what else is lurking beneath the surface, and can these contaminants harm the average drinker?

Smile Like You Mean It

Everyone gets grumpy once in a while, but it’s time to turn that frown upside down— sincerely. Studies suggest a genuine smile better convey trust and kindness while improving the smiler’s mood.

Use a Sit-Stand Workstation

Research has linked sitting for long periods of time to obesity, bad posture, and back pain. Time to combat these sitting-woes and rebel! Get up, stand up for better health and productivity.