I know 4 year olds can be sensitive. However, my DS is too sensitive. If a friend snatches his toy, he'll cry. If he can't understand his homework, he cries. He cries if he finds his work too hard at school (it's not even work, it's colouring in sheets/letters). He cries when he has to go to bed. He cries if his TV program isn't on, etc. etc.
How on earth do you stop this?