Water is the1of all the things we eat and drink. Not many people understand this but2quite true. The human body3go without food for a long time. We've got many examples for this. Yet two4three days without water can usually make people5. Man can't live6water.

    Many people don't understand how7water the human body needs8work well, and many people, especially young people, do not drink enough,9in very hot weather. Our body is mostly water, about 65% to 75%. That is to say about two thirds of our body is water. When we do sports, some of the water will get away from our body.10we don't drink some water, we won't have enough water. If we don't have enough water, we'll feel tired and many of us will get ill. So you know how important water is to us.

    We're sitting too much and it's dangerous. Most Americans spend more than seven hours sitting every day, and the more you sit, the weaker your body will be. Fortunately, there are simple changes you can make during the day—anywhere, even at the workplace—to improve your health.

    Park a few blocks away from the office each morning and walk to work.

    This allows you to start off your mornings actively and be ready to take on the work. If you take the bus, get off one stop earlier to take some light exercise before 8 a.m.

    Get up and move around the office once every 60~90 minutes.

    When you're busy with work, it's easy to forget the time. Set the alarm to remind you to get up and take a walk around the office. You can use this time to fill up your water bottle or go to the bathroom.

    Ask questions and discuss questions face to face.

    Go to your co-workers' office to discuss questions face to face, rather than send an email every time you have a question. This gives you a good excuse to move.

    Use your lunch break to move around outside.

    So many Americans today work during their lunch break. When possible, take advantage of this time to walk outside and enjoy the nice weather. Fresh air can make you keep a clear mind.

The weather is getting hotter and hotter. You are thirsty playing basketball or riding home from school. A cold drink may be just the thing. But be careful what you are drinking. Something that looks cool may not be good for your health.

There are plenty of "energy drinks" advertisement on TV. Most of them have beautiful colors and cool names. They tell you they are helpful to your health. Sounds great and lots of people believe them!

But after a careful check you may find that most energy drinks have lots of caffeine (咖啡因) in them. These drinks are especially aimed at young people, students, busy people and sports players. Makers sometimes say their drinks make you better at sports and can keep you awake. But he careful not to drink too much.

Caffeine makes your heart beat fast. Because of this, the International Olympic Committee has limited (限制) its use. Caffeine in most energy drinks is as strong as that in a cup of coffee or tea. Possible health dangers have something to do with energy drinks. Just one box of energy drink can make you nervous, have difficulty sleeping and can even cause heart problems. Scientists say that teenagers should be discouraged from taking drinks with a lot of caffeine in them.

Feet are an important part of you. Without them, you couldn't stand up, walk or run around. Your feet work so hard that sometimes they get sweaty (出汗).

Think of a hot summer day when you have been walking around all afternoon. Your feet have been in those trainers for a long time! The moment you take off your shoes, you feel good and relaxed, but your feet smell bad. You may think it is because of the sweat. But in fact, sweat itself has no smell. It's the bacteria (细菌) on your skin (皮肤) that mix with it and gives off a bad smell.

Bacteria love dark and wet places like the inside of sweaty shoes. The sweatier you get, the more bacteria there will be. When you wear your shoes, bacteria will have a good meal on your feet. They eat dead skin cells from your skin and then leave a kind of waste called organic acids (有机酸). These organic acids smell bad. Things will become better if you wear cotton socks.