How do you define enthusiasm?
In my current job, I code in perl, java, html, and VB (currently removing the last one). I am what you would call enthusiastic about the perl and java jobs I have to do, I even work on them at home - I just don't show it. I'm not saying you shouldn't show enthusiasm, just relize that some people, for various reasons, don't show emotion very well, yet can both communicate with others and may be brilliant in whatever job there trying to fill.
"Pain is weakness leaving the body, I find myself in pain everyday" -me