Playing football, avoiding junk food or just getting a good night's sleep...
These are things that some people think can help - but what do you think are the best ways to stay healthy?
Do you get your exercise by walking to school, riding a bike or playing sport with friends?
Maybe you're careful about what you eat and have a favourite food that you think keeps you strong and well.
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
"I have a house with a swimming pool and a tennis court. I am a terrible tennis player but I do enjoy going swimming a lot. What I have to remember is that if I go swimming I have to keep my healthy food levels up by eating lots of fruit and veg to give me energy."
Lauren, 10, Nicosia, Cyprus
"I have a trampoline so I burn a lot of calories. Plus, I drink those drinks for calcium for my bones so maybe people should try that, I do!"
Amy, 12, Armadale, Scotland
"I love playing sport and I love eating healthily. I think more people should enjoy eating healthily and staying active. I also think that more people should eat breakfast in the morning because that helps you to stay healthy as well."
Alana, 13, Blackburn, England
"I do swimming and dancing once a week and it keeps me fit and healthy. I eat lots of fruit and veg and sometimes go to badminton. I try my best to cut down on sweets which I do. I go early to bed which is a key thing to keeping healthy."
Molly, 9, Ossett, England
"I think you should stop smoking and exercise every day. I can't exercise too long because I have asthma! Unfair!"
Bridget, 9, Clayton, England
"I just exercise and try not to eat too much junk. It's easy after the first week because you lose the craving of junk."
William, 13, Kent, England
"Horse-riding keeps me healthy! It's fun and it can be pulse-raising! Even mucking out is good for you!"
Bethan, 12, Knighton, Wales
"The best ways to keep healthy are trying not to smoke, following the drinking guidelines, eating a balanced diet and exercising regularly!"
Jodie, 11, Oswaldtisle, England
"I like eating fruit and veg so it is easy for me to stay healthy!"
Aamina, 11, Batley, England
"I think everyone needs a balanced diet. Everyone needs the right amount of exercise and sleep. I walk to school, which is a mile away, so I walk about two miles a day and don't realise it. On a school day, kids should eat breakfast because it helps keep them alert so they aren't falling asleep."
Lizzie, 11, England
"I walk to and from school, I do dancing and swimming clubs, I do dancing in my spare time and I eat healthily."
Caroline, 12, Chatham, England
"I eat what I like! I'm not the healthiest person! I love chocolate and sweets and don't care what people think."
Natasha, 8, Epsom, England
"I think eating a balanced meal and some exercise would be just right to stay healthy. You don't need to stuff yourself with vegetables even if you don't like them."
Nikhat, 13, London, England
"I think it's ridiculous what children are being told nowadays. I never eat fruit (I do have veg with dinner most times) and I'm perfectly healthy."
Kiyo, 13, Preston, England
"I go out almost every night and I eat healthily. The most important meal of the day is breakfast, so before you go to school have a good meal."
Georgia, 10, Cullompton, England
"All you need to do is try to eat your five portions of fruit and veg a day (it isn't always possible!) and do half an hour of exercise a day."
Holly, 11, Brighton, England
"What I say is make sure you eat five fruit or vegetables a day and swap fizzy cola with water. You should drink at least eight glasses of water a day!"
Rebecca, 12, Hevingham, England
"To stay healthy you should have a balanced diet, the right amount of sleep and exercise. It also helps for your body to have a regular routine."
Ashleigh, 12, Durham, England
"Well, I'm a vegetarian so I eat lots of fruit and veggies anyway. I just have to try to get other things like protein. My brother is a vegan, so he has to try even harder."
Harriet, 12, Ryde, England
"Try to eat good food and drink lots of water, that way you are not unhealthy. Also you feel happy instead of eating junk food and always feeling sad."
Rachel, 10, Ely, England
"One hour of exercise every day and eating healthy. Substitute chips for carrots, celery, apples, and other fruits and veggies. I play field hockey every day for school. I also like to play soccer, swimming, and ballet."
Liv, 13, Cincinnati USA
"I think that we should be allowed to eat what we like."
Sam, 10, Maidenhead, England
"I play football twice a week but my mum still tells me to eat better food."
Jessica, 13, Salford, England
"I think you shouldn't try too hard to get fit. All you need to do is go for walks every so often and get out on your bike and play with your mates. That's what I do."
Zara, 12, Crawley, England
"I think eating varied fruit and veg, getting 8-10 hours of sleep AT LEAST every night and only having two chocolate bars a week could help."
Hayley, 11, Bristol, England
"Well, get off the bus a stop earlier or play in the garden after school to substitute. Even run around or trampoline or run up and down the stairs in a TV break!"
Francesca, 11, Wolverhampton, England
"Limit your junk food and do loads of exercise. You sometimes do it naturally by walking, running, jumping, roller-blading, ice-skating and playing football."
Eve, 11, Sheffield, England
"I try to eat five portions of fruit a day and exercise for at least an hour every day. I get at least eight hours sleep every night and don't snack on too many sugary snacks."
Vicki, 13, Cambridge, England
"I walk to and from school, I do dancing and swimming clubs, do dancing in my spare time and eat healthily."
Caroline, 12, Chatham, England
"I think everyone needs a balanced diet. Everyone needs the right amount of exercise and sleep. I walk to school, which is a mile away, so I walk about two miles a day and don't realise it. On a school day kids should eat breakfast because it helps to keep them alert so they aren't falling asleep."
Lizzie, 11, England
"I get plenty of exercise without realising it. I walk to school, run around at playtime, play football at dinner time and walk home at the end of the day. So, I walk about two miles a day without realising it."
Callum, 10, Birmingham, England
"To stay healthy, I do some exercise. I play rugby, hockey and do trampolining. They're all fun so I don't really think of them being exercise!"
Emma, 13, Londonderry, N.Ireland
"My way to keep healthy is to have at least three portions of fruit or veg per day and exercise a lot - it's not hard at all!"
Matthew, 11, Sunderland, United Kingdom