Monotone voice and singing.?

I just started doing karaoke with some friends and I actually like to "sing" now. The problem is that my voice very monotone and makes my singing sound flat which sucks. Basically it doesn't sound like i'm singing but just saying the words. I try to make it sound like Im singing but just sounds like Im talking. So, is there like a real problem I have with my throat or something or I just need to see some specialist?