Asalamualikum,
First of all, be a good example in front of your co-workers. The christians will not harm you, verbally nor other, if so then they are not christian.
of the 75 co-workers that are with me are mostly Christian, and dont seem to understand and look at me with a raised eyebrow
The christians do not understand why you do this. This is your chance, inshaAllah, to talk with them about why you do this. Some christians Fast during Lent...not to the extent that the muslims do....
I watched fellow muslims work together, and saw by their example that something was different in a good way. In time, my ignorance of Islam turned into a blessing.
One thing that I notice in some muslims is that their smile is really important. Always in peace...it seems.
Discussion is good, and not to go into debate. It would be to open doors to understanding why you do this.
Sallam