In the articles that you have read, do they say how many impacts to the head or how many years of playing soccer will put you at risk? I would look for information like that. I don't think heading the ball a few times here and there is going to change your life for the worse. If you're doing it multiple times per day, several times per week, for many years, then it might. Somewhere in between those two extremes is the line between harmless recreation and risky behavior, and as far as I know, it's just not clear exactly where the line is.
It is the cumulative effect of a large number of mild impacts that is of concern. In American-style football, for instance, it has been found that linemen sustain a significant head impact on virtually every play. Formerly, it was believed that only the "ESPN highlight" types of blows to the head could cause brain damage. Now we know that repeated milder impacts can eventually harm the brain. The linemen who were found to have brain damage were NFL players at the ends of their careers -- guys in their mid-30's or older who played organized football, some of them, for more than 20 years. Twenty or more years as a lineman results in a lot of impacts, probably many more, and much harder, impacts than you are going to sustain playing amateur or recreational soccer.
I don't believe there are any neck exercises that will protect your brain. Neck-strengthening exercises might help protect your neck, which is a good thing, but the mechanism of injury from heading a ball is that the brain ricochets back and forth inside the skull. Having a strong neck won't prevent your brain from moving inside the cranium.
Again, look for quantitative information about the risks, and make your best decision. If you can provide us with more detail from your reading about the risks, I'd be interested in knowing that, so please post back if you can. Good luck.
Well, theoretically it is probably not good to head the ball a lot of times. But in practice, if you look at old soccer players they are doing alright. There are other risks in life that are much bigger and worse. The biggest risk with soccer is probably that you collide with somebody and maybe get knocked out unconscious. This can actually kill you. That is the risk, not the impact of the ball.
I don't want to scare you or anything but a lot of bad things can happen to you during your life and when you are old and sit and think back on the worst things that happened to you; diseases, accidents, death of a nearby family member or friend, or other kinds of losses, heading of balls during soccer will not be one of them. I am pretty sure about that.
You are still very young. The worst risks for you are suicide (that is what kills teenagers), traffic accidents, (young men sometimes drive like it is a game, not a means of transportation), that you go out and drink a lot of alcohol and end up in a fight (or traffic accident) that either leaves you injured or behind bars, or that you make some other crazy decision under the influence of alcohol. Eating disorders etc are also a risk.
So basically your biggest risk is yourself these coming years. When you reach 25 these risks go down considerably. Then when you get much older other risks start to come into play, heart disease, cancer etc.
Take care and don't worry to much. Take care of your friends and be safe in traffic and you will be alright:).