Stress can be caused by both good and bad things in your life. What matters is how your body responds: Something that causes another person a lot of stress may leave you perfectly calm.

Stress is a physical response to something you feel threatened by. Anxiety is an emotion that’s triggered by stress -- you feel apprehensive, nervous, or scared.

If you run across a lion in the jungle, your stress response sends more oxygen to your brain, tenses your muscles, and makes your heart beat faster. This is supposed to make you more alert and prepared for action: the “fight-or-flight” response. It works great when you happen upon lions. It’s less useful when you’re just stuck in traffic.

You don’t have to run into a lion to find a use for the stress response. It can show up at the wrong time -- in a conversation with your boss or your teenager -- but it can still be helpful. A little stress-induced anxiety can make your memory and brain work better and may even help make new brain cells. This can help you focus during a crisis at work or if you’re learning a new skill.

Your mindset is a huge factor in how your body deals with it. If you see it as a positive and necessary thing, it’s less likely to take a physical or emotional toll on you.

If it goes on too long, it’s called chronic stress. And in addition to making you more likely to have viral infections, like colds or the flu, this also can cause digestive trouble, a short temper, headaches, and problems with sleep.

When you’re stressed, your liver puts glucose in your blood to fuel the fight-or-flight response. But this can be released when you don’t need it -- say, in a stressful meeting, for example. If you’re already at risk for high blood sugar and it happens too often, it can lead to diabetes. 

You may not notice them at first, but issues caused by work and family responsibilities can add up. If your body doesn’t get a break, stress can cause heart disease, high blood pressure, and depression, among other things.

If you eat comfort foods when you’re stressed (ones high in fat and sugar), the higher levels of certain hormones can turn more of it into belly fat. This is the most dangerous kind of fat because it puts you at higher risk for heart disease.

Women may lose interest in sex if they’re overwhelmed with work or financial problems. But it can cause that and more in men. It can lead to erectile dysfunction and affect testosterone -- a hormone linked to sexual interest and performance -- as well as sperm quality and the ability to make them.

Migraine headaches and tension headaches are thought to be caused by this. When muscle tension affects your whole body, it can cause constant pain and inflammation.

Just 30 minutes a day of moderate exercise can help boost your mood and limit the negative effects of stress. And you get even more out of it if you go outside in the sunshine.