Bullying, school, climate change...
It seems there are lots of things for kids to worry about these days.
This is one of the issues Newsround is looking at as we try to find out what you think of the world you're growing up in.
But what are kids in your country most worried about?
Bullying, war, and street crime.
Charli, 12, Leicester
My town is in the top three worst ASBO places in Britain and nobody is doing anything about it!
Kimberley, 13, Nottingham
I'm worried about pretty much everything and I know that right now, I'm powerless to change anything.
Osnat, 10, London
Crime is quite worrying because it's happening everyday. And the war in Iraq is also a big problem in the UK.
Yasmeen, 11, Surbiton
I'm worried about all the wars between countries. And I'm scared if my country gets involved too.
Rabia, 13, Dubai
The people in Africa and poor places like that, and also global warming is a big thing too.
Rosie, 10, Thornbury
I think the main problem in the world is money, tax and things like poverty and aid and other illnesses.
Chaz, 13, Bournemouth
They keep chopping down trees where I live, so fewer animals have homes.
Jonah, 12, USA
I'm worried about crimes.
Kristina, 12, Cheshire
I'm worried about children in Africa and about climate change. I don't want all the animals to die out or the temperature to rise a lot.
Sophie, 12, Isle of Man
I think anorexia is a big problem for teenagers because they want to look like celebs.
Amelia, 12, Salisbury
Bullying seems to be very common where I live, and I don't like it.
Rhys, 11, Glasgow
I think a lot of kids worry about bullying and being fat because all the celebrities are all dead thin.
Rebecca, 11, Newcastle
Safety is probably the biggest issue. Also climate change is another.
Zoe, 13, Southampton
Sometimes I have trouble at my school because some people bully me.
Beth, 7, Eastbourne
I think most of the problems come from peer pressure, I know loads of kids my age that smoke and steal because they think it's cool.
Fran, 13, Launceston
Well, I'd say things like Global Warming. There are all these kids out there who want to be like Steve Irwin was and David Attenborough is! Unfortunately, they won't get the chance because of the huge numbers of biomes, habitats, plants and animals affected by Global Warming!
Ellie, 10, Mirfield
Me and my friends worry about going to senior school and what's happening to the planet.
Sam, 10, Essex