What is the main topic of the talk? The main topic of this talk is to offer advice on ______.

Do you find yourself tired all the time although you get enough sleep? Then maybe this is for you. When you’re feeling weak and tired, the worst thing to do is to take a short sleep. It won’t restore your energy. On the contrary, what happens then is your body loses even more energy than it had before, making you even more tired.
   You may also have these poor habits that worsen the problems. Do you stay in the same area without getting up to move around? Does your job require that you sit down the whole day in front of a computer? Any of these reasons might be the cause of your energy loss, keeping your energy level low.
   What should you do, then, at those moments when you feel so tired even though you’ve got enough sleep? A cup of coffee won’t help much either, as it is easy to get addicted to the caffeine. The best and most natural thing to do is to take a short walk. Doctors suggest the activity because it will increase the heart rate. This increased heart rate will lead to several hours of alertness. Moreover, a regular exercise routine can make your tiredness problems disappear forever.
Question 11: What is the main topic of the talk?