By now most of us have heard that nature is basically a wonder drug for humans. Having evolved out of doors, our bodies and minds respond to open spaces in impressive ways, reducing our stress and risk of depression, and boosting creativity and happiness.

But that raises the inevitable question: how much nature exactly do you need to see these benefits? Lots of us would like to make time for weekend-long camping trips or 20-mile hikes but live in tree-deprived urban environments. Escaping the city isn't always possible.

Studies have found benefits from actions as simple as gazing at a green roof for 40 seconds or putting a potted plant on your desk, but the effects, while meaningful, are modest. How much nature do you need to reap the full rewards of this powerful wellness booster? A new study offers an encouraging answer.

Got two hours a week?

The findings come from a massive new British study that looked at the daily activities of 20,000 people over the course of a week. It was designed to answer a medical question that previously stumped doctors.

Patients "are coming to us and saying 'Doctor, how long do I have to spend?'"  commented the study's lead author, psychologist Mathew White, to our sister publication Fast Company. "And doctors are saying, 'We don't really know.'" 

After the researchers analyzed the data, medical professionals now have a conclusive answer. No need to pack a tent. Even fancy hiking boots are probably optional. All you need to do to experience the incredible health and happiness-boosting benefits of nature is to go outside for a measly two hours a week.

You don't even have to break a sweat to experience benefits. Nature is good for you even if you just plontz your butt down on a blanket in a park, the researchers found. Though you do have to actually escape the urban jungle. Looking at a sickly tree stuck in the sidewalk on the way to the deli doesn't cut it. Finding wide open spaces like a park where you can be fully immersed in a natural environment is key.   

White was as relieved as the rest of us to find such a doable number. "We were really relieved it was two hours and not 12 hours," he said. "This could be accumulated over the week: A half hour here, half an hour there, and before you know it, you know, you've achieved two hours."

Despite the good news about how little nature makes a difference, the study found 60 percent of people weren't notching up even two hours a week. No wonder doctors in the UK are already prescribing time in nature to patients with a variety of complaints.

Maybe you should follow their lead and prescribe yourself two hours in nature this weekend.