I really believe in letting the boy figure out things for himself. I much prefer to help him and guide him to wards things than to lead him out right.
Now having said that I will tell him if something is a bad idea and let him know what the possible consequences are. But he still wants to do it and it won't actually harm him, then I'll let him find out for himself. Ben is pretty mature for his age so this works well for us.
Sarah "We have to wait until next time."
Ben "But why Mummy, there are lots of empty seats!"
Sarah "Yes there are, but they only allow one adult per ride, and that man is going, right now."
Ben "But I can go by myself"
Sarah "Yes you can but I don't think you realize how scary that thing is. I think you should wait until next time so I can be beside you."
Ben "But I don't want to wait I want to go NOW."
Sarah "Okay dude, it's your choice. Are you really sure you want to go on that scary ride all by yourself?"