Learning in the ring

Apparently I have issues with going light in the ring while sparring. And I'm not sure exactly what the cause is. I do know one thing - I tend to speed up and hit harder when my Kru is watching me. If he's not there, I go lighter, feel like I can relax.

What is that caused by? Is it ego getting in the way? The need to prove myself to him? Is it nervousness and me getting all spastic when an authority figure is watching and judging? Is it the fear of looking like a moron in front of a teacher? Maybe it's a mix of all of these factors in varying degrees. But what I do know is that I have to solve this problem so I don't keep hearing "lighten up" again and again. I understand the concept. But I seem to have problems putting it into action in certain situations.