When the temperature-humidity index approaches triple digits and the air quality index is less than poor, it’s time for indoor hiking.

If you’re on your feet for three or four hours, you’ll burn somewhere between 600 and 1,000 calories while you, like Alice in Wonderland and the Jefferson Airplane, feed your head. We’ll talk about lunch later.

I just did this at my local museum, The Metropolitan Museum of Art. You can do this at yours even if its corridors don’t provide quite as much open mileage. The Met is four city blocks long; that’s .2 miles. My Met Trail Map winds through and around many of its galleries for a 3- or 4-mile walk.

Before we get started, here’s the idea. We cruise and peruse for the distance. No speed walking; you don’t want to annoy others or attract the attention of security. On your copy of the museum floor plan, note the locations of the works you want to return to for a Better Slower look.

Through time and space
After you climb the entrance staircase, buy your admission ticket and marvel at The Great Hall: head south down the long hall of Greek and Roman Art. Big, long, smooth strides like the gods and goddesses that surround you. Step quietly into the galleries to the right and the left. Make your way around the massive column and into the new skylit Courtyard. Feel like Youthful Hercules. C’mon, use your imagination. Follow my trail on the detailed map and you’ve already covered .2 miles.

Now go from polished marble to ochre- and mud-rubbed wood and fiber. Weave through the many galleries of The Arts of Africa, Oceania and the Americas. If you actually follow my trail during the next two months, you’ll be able to see – but not play – a fascinating collection of musical instruments from Oceania. Another .2 miles out from under your belt.

Next time warp: right into Modern Art. A couple dozen small galleries to explore Picasso, Matisse, Bonnard, Balthus, Boccioni; then the stairs to the mezzanine for great modern painting and great views of Central Park, the Museum’s backyard. Down the stairs at the other end of this exhibit area and north into …

European Sculpture and Decorative Arts. Almost a half-mile of masterworks, from Bernini to Rodin. Architectural settings, period rooms, furniture, jewelry, and tapestries. Lots of Art History 101’s Greatest Hits.

Next: a quarter-mile lap around the spectacular Lehman Wing Atrium, with ten detours into the side galleries. Yes, those really are Goya, El Greco, Rembrandt, and the Impressionists.

More time and space travel: follow the trail through Medieval Art – and be sure to find your way into Arms and Armor. Be glad you don’t have to wear that suit in this weather. A third of a mile through the Bronze Age, the Byzantine and Early Medieval.

From the Dark Ages to the brightly sunlit glass cube of The American Wing. Don’t let the sheer beauty of this big, open space grab your full attention. There’s a quarter-mile of American sculpture; stained glass by Tiffany and Saint-Gaudens; period rooms and portraits.

Here at the north end of the museum, head west to another dramatic space. This one preserves the Temple of Dendur in its entirety, as it appeared on the banks of the Nile. A few laps around the perimeter; when you’re done with this mesmerizing quarter-mile, you’ll be in Egypt, c. 15 B.C.

Now you make your way through the many galleries of Egyptian Art. 1/3 mile, 6,000 years, 36,000 objects. Jewelry, statuary, tombs.

And here we are, 2.5 miles and an hour or two later, back at the Great Hall. Time to climb the Grand Staircase.

Upstairs, a mile or two more to see more than a hundred galleries. Chinese Art. Japanese Art. Korean, Southeast Asian, Ancient Near Eastern and Islamic Art.

And then you enter the 19th and Early 20th Century European zone. The iconic paintings of Cezanne, Monet, Pisarro, Renoir, Van Gogh, Degas and Manet. Prints by Durer, Goya and Rembrandt. It’s OK to stop whenever you just have to.

And if this isn’t enough for you – go to The Met’s Roof Garden before October 31 to have your mind blown by Big Bambu, a monumental bamboo structure. You can walk around it anytime; you need to reserve a tour time if you want to make your way up and down its winding ramps.

What if I’m not in New York?
Doesn’t matter. There are great museums everywhere. If you’re not an avid or even regular museum-goer, you don’t need The Met to have an amazing experience. Take the cruise and peruse approach. Get some exercise and see it all at a glance. Then go back to the things that really caught your eye. It’s almost a sure thing you’ll be making return trips to rediscover all of them.

Last year, I had a wonderful half-day walk through the Joslyn Art Museum in Omaha, Nebraska, USA. You probably never heard of it. If you’re near there, go take a walk.

Dont just sit there!
Even if you exercise for an hour a day, you’re still awake for another 15 hours. If you spend too many of them sitting, you’ll have significantly higher risk of “cardiovascular disease, type 2 diabetes, metabolic syndrome risk factors, and obesity … because any type of brief, yet frequent, muscular contraction throughout the day may be necessary to short-circuit unhealthy molecular signals [from prolonged sitting] causing metabolic diseases.” American Diabetes Association, “Role of Low Energy Expenditure and Sitting in Obesity”.

So go the the museum, not the movies. Museum air-conditioning is the best – they have to control temperature and humidity to preserve the artworks. Take a great indoor walk and feed your head; don’t sit on your butt and chew popcorn.

Speaking of your butt, take the stairs, not the elevator. You’ll activate, stretch and strengthen your gluteus and hamstring muscles walking upstairs.