When I ask women to be happy around their husbands, I get this response once in awhile. They feel that if they try to act happy when they are not, they are being a hypocrite. I'm reading a great book by Martha Peace called "The Excellent Wife" and she made the statement, "I am never being a hypocrite when I obey God in spite of my feelings."
So just because you don't feel happy, doesn't mean you shouldn't act happy. God wants us to be joyful and rejoice always. Just because you are grumpy and feel like being mean, act kind anyways because God wants us to be kind. It is called self-control...Doing what you know is right even when you don't feel like it.
As you practice happiness and kindness, it gets easier. Right now you may be practicing grumpiness and meanness. Start practicing happiness and kindness. It'll get easier the more you practice it. Your life and those around you will be much better. Promise!
Rejoice in the Lord always. I will say it again: Rejoice!
If ye know these things, happy are ye if ye do them.