Playing Guilty

Yesterday, Oakcrest chess team defeated Burlington chess team.  I was board 5 Varsity.  I played against a JV member that had been moved up because their board 3 couldn't make the match. 

I remember doing well in the beginning and being a bishop ahead already.  I felt guilty while playing.  I went a little easy and made some mistakes that i overlooked but he didn't see them....  -__-'  i ended up just playing seriously toward the end, though it appeared not to be...  (to Oakcrest chess team that was looking at the match, you know what i'm talking about...  ^_^')

Has anyone here ever played someone and felt so guilty that they kinda just let go a little during the match before actually playing seriously again?  Does anyone have any tips on playing all out regardless?  ^_^'  I can't seem to do that yet....