Is Being Sad a Sin?

I am sad. A lot. I have had well meaning Christians tell me that being sad all the time is a sin. They also say being sad is being ungrateful. I can't always help that I am sad. I think it is sometimes the only response I know how to have. So is being sad a sin? 

I don't think that it is. I hope that it is not. Trusting that Michele is correct and I won't be sad forever. Trusting scripture is right that God will turn my mourning into dancing... I am ready God let the music start.