Need help with Interview question

I recently changes jobs and have been at my noew job for about 5 months. I was at my previous job for 5 years. My new job was just not cuttin git for me so I decided to keep on looking. Well, I got an interview and was wondering how to approach answering this question:

“Why do you want to leave your current job so soon?”

Should I tell them the truth even though it may turn out to be more negative then positive and hurt my chances?

Any sugesstions or personal stories would be very helpful.

Thanks,