In the 1964 movie "Mary Poppins," one of the first things nanny Poppins does when she arrives at the Banks' house is unpack.

To the shock of her new charges, Jane and Michael, she pulls massive items out of her carpetbag: a hat stand, a large mirror, a tall houseplant, and finally a standing lamp.

Okay, that’s a little bit much. But we've noticed that in real life people are loading their totes with some pretty weighty stuff too — computers, books, tablets, phones, gym shoes, lunch, water bottles)

That’s the kind of stuff that can cause serious neck, back, and shoulder problems.

Research shows that carrying a heavy load on one shoulder strains the trapezius, a back muscle covering most of your upper back and the back of the neck, and the erector spinae, a series of muscles that run up the back from your tailbone to your head.

You also can cause tendinitis or irritate your shoulder bursa (the cushion in your shoulder joint), causing bursitis.

One small study even found that regularly carrying a bag on one side can alter your gait.

So ignore online articles proclaiming "20 Things Every Modern Woman Should Have in Her Purse," and "13 Things Every Man Should Carry in His Bag," and get rid of the nonessentials.

Still shoulder-breaking? Divide the contents into two bags. Carry one on each side.

Better yet, consider a rolling computer/briefcase (wheels really were a great invention) with dual backpack straps for when you need to carry it around.

For a healthy back and shoulders, you need to lighten your load.