At what age do we grow up...understand consequences for our actions, etc.?

What age do you think we should stop with the "Whoo Hoo, it's the weekend! Party time!" attitude and be more subtle about enjoying life? I mean, how many times does a person in his 40s wake up with a hangover until he puts 2 and 2 together and be more moderate? Or pout because your friend is off work on a Friday night, but you have to work late? So tired of the complaining and whining!!!