A strong memory depends on the health and vitality（生命力）of your brain. They say that you can't teach an old dog new tricks，but when it comes to the brain，scientists have discovered that this old saying simply isn't true. 【小题1】

Give your brain a workout. Memory, like muscular strength, requires you to“use it or lose it”. The more you work out your brain, the better you' ll be able to process and remember information. 【小题2】

Don't skip the physical exercise. While mental exercise is important to brain health, that doesn't mean you never need to break a sweat. Physical exercise helps your brain stay sharp. It increases oxygen to your brain and reduces the risk of disorders that lead to memory loss.

Get enough sleep. There is a big difference between the amount of sleep you can get now and the amount you need to function at your best. 【小题3】

Keep stress in check. Stress is one of the brain's worst enemies. Over time, stress destroys brain cells. Studies have also linked stress to memory loss.

Have a laugh. 【小题4】 That holds true for the brain and the memory, as well as the body. Unlike emotional responses, which are limited to specific areas of the brain, laughter involves multiple regions across the whole brain.

【小题5】 Just as the body needs fuel, so does the brain. You probably already know that a diet based on fruits, vegetables, whole grains,“healthy”fats and lean protein will provide lots of health benefits, but such a diet can also improve memory. For brain health, though, it's not just what you eat — it's also what you don't eat.

How teens can stay fit

Any type of regular physical activity can improve your fitness and your health.【小题1】

Exercise should be a regular part of your day, like brushing your teeth, eating and sleeping. It can be in a gym class, joining a sports team, or working out on your own. Keep the following tips in mind:

【小题2】A good attitude is important. Find an activity that you think is fun. You are more likely to stick with it if you choose something you like. A lot of people find it's more fun to exercise with someone else,so seek a friend or family member to be active with you.

Take it one step at a time.【小题3】For example, walk or ride your bike to school. Get on or off the bus several blocks away and walk the rest of the way. Use the stairs instead of taking the elevator.

Get your heart pumping. Whatever you choose ,make sure it includes aerobic （有氧的) activities that make you breathe harder and increase your heart rate. This is the best type of exercise because it increases your fitness level and makes your heart work better.【小题4】Examples of aerobic activities are basketball, running, or swimming.

Don't forget to warm up. Do  some  easy exercise or stretch （伸展) before you do any physical activity.【小题5】It is also important to stretch out after you exercise to cool down your muscles.

   With an improved economy，many travelers have been buying first or business class seats，leaving fewer for upgrades（升级）.Here are some strategies for getting a free upgrade.

1. Fly a lot.

This is the most common way to earn a free upgrade. Most airlines reserve some spaces for travelers who fly at least 5，000 miles per year. Five years ago，this meant half or more of domestic（国内的）first class travelers sat up front for free. But now，airlines are selling more high-price seats，so on popular routes it is not unusual for more than 20 travelers to compete for one or two upgrades. But on routes with fewer business class travelers，free upgrades remain more plentiful.

2. Use miles.

If you're not a frequent traveler but still have some miles to fly，you may be able to use them for an upgrade. Be careful，though，as many airlines now ask not just for miles but also a cash co-pay. One example: on flights to Europe，American Airlines charges 5，000 miles，plus $110，for a one-way upgrade from discounted economy class to business class. For most domestic upgrades，American Airlines wants 15，000 miles plus $ 75.

3. Get lucky.

Sometimes airlines overbook coach（经济舱），and a few travelers get no seats. Agents try to ensure the airline's most loyal travelers get the nod（被选中）. Agents usually have some flexibility to make sure the plane is full and takes off on time. So it's the easiest way for them to do it-they might upgrade someone else out of order.

4. Save a life.

Flight attendants don't usually upgrade passengers, even when empty seats remain. Doctors and nurses who answer an emergency call are sometimes an exception. If they comfort a passenger, flight attendants might allow them to sit in business or first class for the rest of the flight.

   Many people want to achieve success in life, but it's easier said than done because there are so many distractions(分散注意力的事). Then how to be successful? 【小题1】

Imagine becoming successful.

Einstein said imagination is more important than knowledge. The more carefully you imagine your success, the easier it will be for the rest of yourself to follow through. 【小题2】 What is your success like? Taste the feeling of your success, and use it as motivation(动机)to encourage yourself.

Find the purpose of your life.

Find out the things you love to do, and use this information to find the purpose of your life. Finding what you love to do will give you motivation along the way. 【小题3】 Pretty difficult, right? Now imagine the opportunity to join in a chess game. It's much easier to achieve your goal if that is what you enjoy.

Surround yourself with people who are successful.

When you're surrounded with people who are highly driven, it's encouraging. 【小题4】 Model some of your ways around theirs, if possible. Knowledge is as free as it is powerful.

Collect as much information as you can.

Listen. Study. Understand. Learn. Repeat. Humans are amazing creatures because we can look at the world, make intellectual(理智的)connections,and use those connections to make our lives better. This is what information allows us to do. 【小题5】 You never know when your flash of wisdom will come!