Excitement gone

Hi, I started dating a guy a couple of months ago that i work with. I was really into him and loved seeing him everyday but now the excitement has kinda faded. He sits 5 rows over from me and i can see every move he makes. We maybe see each other twice a week outside of work and never cling to each other at the office. I really like his personality and i am completely attracted to him so why have i suddenly lost the excitement of seeing him? Any advice on what i should do?