Hi there

Even though I'm relatively new to boxing, I know what nerves can do to you. Back when I used to swim, whenever a really important race came up, my arms and legs would just go. My strength would ebb and fade faster than I thought possible, even though I had prepared extensively for the race. It took me a long time before I learned to relax before a race.

If nerves are indeed a part of it, I would suggest that you try to stay loose. Relax, shake out your limbs, and be secure in the fact that you've prepared for this exact thing.

If conditioning is a part of it, I concur with cnote - work it til' it burns

Good luck