Some kids have never tasted chocolate, candies, juice, french fries, or even McDonalds till they are much older. Some kids ate so much of these stuff that their baby teeth fell off prematurely. Rule of the thumb, eating in MODERATION.

And there are parents who strictly forbid iPad, TV, computer games in toddler-hood. They will share highly intelligence articles on Facebook on how destructive these modern devices are. Well, Roger works for Disney Animation, can you imagine how these parents hated him for creating highly addictive "Let It Go" movies? Hahahaha! Rule of the thumb again, playing in MODERATION.

So, I realize that the seemingly outdated psychology theory which I learned in Uni years ago was quite useful after all. It's "positive reinforcement vs punishment" Reward your kids with moderate amount of treats and play time when they are behaving correctly is after all, not a modern catastrophe. Don't be too hard on yourself or your kids, let them grow up happily and healthily. As for those Facebook articles, I view them as "modern chain letter", hahahahahaha.

Positive Reinforcement: adding something in order to increase a response. (e.g. adding a treat will increase the response of sitting; adding praise will increase the chances of your child cleaning his or her room. The most common types of positive reinforcement are praise and rewards.
Negative Reinforcement: taking something negative away in order to increase a response.  Imagine a teenager who is nagged by his mother to take out the garbage week after week.  After complaining to his friends about the nagging, he finally one day performs the task and to his amazement, the nagging stops.  The elimination of this negative stimulus is reinforcing and will likely increase the chances that he will take out the garbage next week.
Punishment: adding something aversive in order to decrease a behavior. The most common example of this is disciplining (e.g. spanking) a child for misbehaving. The reason we do this is because the child begins to associate being punished with the negative behavior. The punishment is not liked and therefore to avoid it, he or she will stop behaving in that manner.
Cited from Dr. Christopher L. Heffner