How do I become less sensitive? (I am male)?

I ve been boxing for a couple months now and I think I m quite alright, but if anything I just want to stay in shape. Although it s not my intentions the main idea of the sport is fighting and I can still use it for self-defence. The problem arises when I spar because when I get hit by a hard punch, or throw a hard punch I start crying. I dont know why but I am just so sensitive. The more and more I spar nothing gets better. Is there anything to help me become less of a p**** (I dont know if yahoo answers bans swear words(