Don't get too deep in it. Smoking at a party or concert or whatever is alright, but if you literally just sit in your house and blaze up all day, you will lose track of time and just do not shit.
Also, no one has mentioned the legal issues yet. In the US where I live, I had a buddy with 1/4 of a gram in his car and he lost his license, went on his record, and paid over $2000 in court fines and lawyers for it.
I started weed at 13 (still 13 lol), weed won't kill you. It won't fuck up your life IF YOU CAN CONTROL YOURSELF. Weed actually has a positive effect on your life, it makes you happy and is a getaway from irl. Weed is also seen as a "gateway drug", meaning you'll get into other drugs after smoking weed. If you can prevent yourself from doing this, you'll be fine. Basically all other drugs aren't like weed, weed won't kill you, while other drugs have the possibility too. If you can keep your smoking to a limit, put irl first, and not use other drugs, you'll be fine.
I'm 16 right now and i do it. And im perfectly fine just don't do it everyday i do it couple times a month and i'm doing great. Don't believe all these bad things about weed there's nothing wrong with it.
As djweasel previously stated, you are young and it does have more of a possibility of having a negative influence on your growth as an adult.
Either way abuse of anything, including Marijuana can do serious damage to anyone's life. If you can use marijuana responsibly while keeping up with school and any other important thing you have to do, then go ahead. If you can't do that now, stop smoking and re-evaluate the situation when you are a bit older.
Marijuana is not a "gateway drug." I personally think pills caused me to go deeper. I can now control all this and managed to just stay with weed.

