Your immune system is like a superhighway -- a network of channels and nodes that delivers immune cells and removes pathogens via a clear liquid known as lymphatic fluid. The key to keeping it free of blockages? You need to move, says Katy Bowman, a biomechanical scientist and the director of the Restorative Exercise Institute in Ventura, California. "If your muscles are tight or you're mostly sedentary, the lymph nodes accumulate waste and decrease your ability to fight illness," she says.

Stretching and walking stimulate the flow of lymph and thus your immune system, Bowman says. Think of it as traffic management -- clearing any bottlenecks so your body can flush out invaders and help you stay sniffle-free this winter. Bowman recommends doing this routine before and/or after a 45-minute walk most days of the week. If it's too chilly outside for a walk -- or if you feel a cold or sore throat coming on -- the stretches alone will stimulate your defenses. They target the areas with the highest concentrations of lymph nodes, as well as the intercostal muscles (between the ribs) to help you breathe better.

What it does: Moves lymph through the throat and neck and soothes sore throat muscles.

How to do it: Standing or sitting with chest lifted and shoulders moving down, allow the head to drop forward. Relax and hold for 30 seconds.

What it does: Opens the hips and encourages better lymph flow through the large nodes in the groin.

How to do it: Lie on the floor with sit bones against the wall. Reach legs up the wall and allow legs to drop open as far as you can while keeping them straight. Rest here for 1 to 2 minutes.

What it does: Opens and strengthens the muscles between the ribs.

How to do it: Lying on your back, interlace fingers and reach arms overhead until wrists touch the ground. Keeping feet and hands on the floor, walk arms and legs to the right as far as possible. Cross left ankle over right to increase the stretch. Breathe into left side of rib cage to stretch the "coughing muscles"; hold for 1 minute. Repeat on the other side.

What it does: Opens lymph sites in the chest, lungs, armpits, and neck, and stretches the muscles used to cough.

How to do it: Place hands on the back of a chair and walk back until arms and spine are fully extended. Keep legs straight and tailbone slightly lifted as you sink spine toward the floor and allow your head to relax; hold for 1 minute.

What it does: Strengthens the muscles between the ribs, resulting in more efficient breathing and more productive coughs.

How to do it: Tie a resistance band or pair of tights around your torso just beneath your breasts (where your bra strap sits). Stand up tall and breathe deeply so that your rib cage expands into the band; take 10 to 15 breaths.

What it does: Opens the armpits and chest, encouraging the flow of lymph.

How to do it: Place a stack of pillows or folded blankets on the floor and rest head, neck, and shoulder blades on them. Reach arms out to the sides until hands touch the floor. Sweep arms up overhead and back down for 1 minute, as if you were making a snow angel. Try to keep your hands in contact with the floor.

What it does: Pumps lymph through lower half of the body.

How to do it: With hands on hips, stand on one leg and swing the other leg forward and back, mimicking a vigorous stride while maintaining balance. Be sure not to compress the lower spine; minimize movement at the low back by not leaning forward. Do 20 swings with each leg.

What it does: Stimulates lymph flow through the armpits, chest, and lungs.

How to do it: Stand with feet hip-width apart, arms straight by your sides. Swing one arm forward and the other arm back for 1 to 2 minutes, lifting the back arm without pushing your rib cage forward.

Walking Tip
To encourage the flow of lymph, swing your outstretched arms and lengthen your strides behind you, Bowman says.