Sorry in advance if I repeat some tips already posted, these are just what spurs me on.
To be honest, I'm not good at crosstraining, or even any machine...I find I get way to exhausted too quickly and can't go on. I do aerobics, it gets the heart rate up just as quickly and that way I have the instructors spurring me on aswell!! They have a counter which shows how far you've come and how far you have to go so and you get familiar and know how long you have left!
But, when I do work on machines, I tend to try to NOT think of the exercise. I "day dream", about anything...from what I want to look like when I'm thin, To how people will comment, or showing off my new body..things like that.