Next time you are in the simulator try closing your eyes and setting what you think is a reasonable go around thrust. On the 737-800 the relevant number would be about 88% N1 at a normal landing mass of around 63 tonnes. Keep practising until you develop the " muscle memory" for the correct N1. Then when you press TOGA, advance the thrust levers and call " Go Around Flap 15 Check Thrust" or whatever your SOP calls for the PM will only have to make minor adjustment if any to the N1 to achieve the desired performance.