Captain Stable brings up a sad point ... that of enthusiasm. It has been my observation that many pilots lose the value of the sim as a Training (with a big capital T) tool and are motivated by the "it's a pain to be got over with ASAP" attitude.
However, with a little bit of encouragement (sometimes, a bit of pushing) most pilots seem to be keen to have a go and test themselves against their own perceptions of manipulative skill standards.
I suspect that the main need is to convince them that there is NO penalty to be had if they don't achieve some nominal goal .. that is ... it is just a practice and skills improvement exercise.
Makes you wonder what sort of environment some instructors/check pilots must create to generate the unlying fear of criticism problem ..... it is quite amazing just how much better a pilot can perform if he/she can relax and not worry about the fact that someone might be looking at the performance.