Staying healthy comes down to a handful of habits that, done consistently, dramatically cut your chances of catching colds, the flu, and other common infections. None of them are complicated, but the details matter more than most people realize. Hand hygiene alone reduces respiratory illnesses by 16 to 21%, and layering several strategies together offers even stronger protection.
Wash Your Hands for a Full 20 Seconds
This is the single most effective everyday habit for avoiding illness. Scrubbing your hands for at least 20 seconds removes significantly more germs than shorter washes. That means lathering with soap and rubbing all surfaces of your hands, including between fingers and under nails, for the time it takes to hum “Happy Birthday” twice. The 20 seconds refers to the scrubbing portion, not the entire process. Rinsing and drying add another 20 to 30 seconds on top of that.
The moments that matter most: after using the bathroom, before eating or preparing food, after blowing your nose or coughing, and after touching shared surfaces in public spaces like door handles, elevator buttons, or shopping carts.
When soap and water aren’t available, hand sanitizer with at least 60% alcohol is a solid backup. Sanitizers in the 60 to 95% alcohol range kill germs effectively, while those below 60% only slow germ growth rather than eliminating them. Check the label before you buy. Keep a small bottle in your bag, your car, or your desk drawer.
Sleep 7 to 9 Hours a Night
Your immune system does critical repair work while you sleep. During those hours, your body produces protective proteins called cytokines, some of which directly fight infection and inflammation. When you’re short on sleep, production of these proteins drops, leaving you more vulnerable to whatever virus is circulating at the office or your kid’s school.
The target for most adults is 7 to 9 hours per night. Not just time in bed, but actual quality sleep. If you’re consistently getting six hours and wondering why you catch every cold that comes around, this is likely a major factor. Prioritizing a consistent bedtime, keeping your room cool and dark, and cutting screen time before bed all help you hit that window reliably.
Keep Stress in Check
Chronic stress doesn’t just feel bad. It actively weakens your immune defenses through a well-documented biological pathway. When you’re stressed for extended periods, your body keeps pumping out the stress hormone cortisol. Short bursts of cortisol are fine, even useful. But when levels stay elevated for weeks or months, cortisol starts killing off immune cells and suppressing their function.
Specifically, prolonged stress depletes your supply of T cells, the white blood cells responsible for identifying and destroying infected cells. It also weakens your macrophages, the immune cells that engulf and digest pathogens. The result is a body that’s measurably worse at fighting off infection. Research on depression and chronic stress consistently shows increased susceptibility to illness.
What counts as stress management varies from person to person. Regular physical activity, adequate sleep, social connection, and time spent on activities you enjoy all lower cortisol over time. The specific method matters less than whether you actually do it consistently.
Move Your Body, but Don’t Overdo It
Moderate exercise strengthens your immune system. Aim for 150 to 300 minutes per week of moderate-intensity activity, which lines up with recommendations from major public health agencies worldwide. Walking briskly, cycling, swimming, or doing yard work all qualify. Regular moderate exercise lowers your risk of upper respiratory tract infections, the category that includes colds and many flu-like illnesses.
There’s an important flip side, though. Strenuous, prolonged exercise can temporarily suppress your immune system for anywhere from 3 to 72 hours afterward. During that window, your immune cell counts drop and their function declines, making you more susceptible to infection. This is particularly relevant for marathon runners, people doing intense daily training, or anyone suddenly ramping up workout intensity. If you exercise hard, pay extra attention to sleep, nutrition, and hygiene during recovery periods.
Stay Current on Vaccines
Vaccines remain the most targeted defense against specific illnesses. For healthy adults, the key annual vaccine is the flu shot, recommended as one dose every year regardless of age. Adults 65 and older benefit from the high-dose or adjuvanted versions, which produce a stronger immune response.
COVID-19 vaccination is also updated annually. Adults under 65 are recommended to get at least one dose of the current season’s vaccine, while those 65 and older are recommended two or more doses. RSV vaccines are now available for adults 50 and older, with particular emphasis on those 75 and up. If you’re unsure what you’re due for, a pharmacist can typically check your records and administer anything you need in a single visit.
Keep Indoor Humidity Between 40% and 60%
This one surprises most people, but the humidity level inside your home plays a real role in virus transmission. Research has found that maintaining indoor relative humidity between 40% and 60% is associated with lower rates of respiratory infections. Below 40%, the air dries out your nasal passages (reducing their ability to trap pathogens) and allows virus-carrying droplets to stay airborne longer. Above 60%, you risk mold growth, which brings its own set of health problems.
A simple hygrometer costs under $15 and tells you where your home stands. In winter, when heating systems dry the air out, a humidifier can bring levels up into the protective range. In humid climates, air conditioning or a dehumidifier keeps things from climbing too high.
Get Enough Vitamin D
Vitamin D plays a measurable role in respiratory infection prevention, but the way you take it matters. A large meta-analysis reviewed by the World Health Organization found that daily vitamin D supplementation reduced the risk of respiratory infections, while large monthly or quarterly mega-doses did not. The protective effect was strongest at lower daily doses (under 800 IU per day), taken consistently rather than sporadically.
Many people are deficient in vitamin D, especially those who live in northern latitudes, spend most of their time indoors, or have darker skin. A blood test can confirm your levels. Food sources include fatty fish, fortified milk, and eggs, but supplementation is often the most practical route for people who are low.
Reduce Contact With Your Face
Cold and flu viruses commonly enter your body through your eyes, nose, and mouth. They get there when you touch a contaminated surface and then touch your face, something most people do dozens of times per hour without realizing it. Respiratory viruses can survive on hard surfaces for several hours to days, depending on the surface type and the specific virus. Soft, porous materials like fabric tend to deactivate viruses faster than hard, smooth surfaces like countertops or phone screens.
Building awareness of this habit is the first step. Keeping your hands clean makes face-touching less risky when it inevitably happens. Regularly wiping down your phone, keyboard, and other frequently touched objects adds another layer of protection, particularly during cold and flu season or when someone in your household is sick.
Masks Work Best When You’re Already Exposed
Wearing a mask in everyday public settings during cold and flu season offers some protection, though the evidence is less dramatic than you might expect. Large trials comparing N95 respirators to standard surgical masks in healthcare settings found no clear difference in rates of confirmed influenza infection. Both types of masks provided modest reductions in flu-like illness symptoms overall.
Where masks provide the clearest benefit is in higher-risk situations: caring for a sick household member, visiting a crowded indoor space during a major outbreak, or protecting yourself if you’re immunocompromised. For the average person during a typical flu season, the habits above, consistent hand washing, good sleep, exercise, vaccination, and humidity control, deliver more reliable protection than wearing a mask to the grocery store.