The good trainer can find your personal motivations and this can give your excercise to a boost, because he/she just can find the right moment telling "I can see you go on your way well." or "Okay then, let's climb a mountain together because now you can do it!"
My spinning trainer is an Iron Man, he does several challenges and races every season and you can jsut see how he loves sports. He goes on further trainings to improve his and others' technique and performance.
As I'm doing a pulse-controlled, 24 weeks long programme with him in which I finished the 1st phase, he told me this is my personal Iron Man. Because you can find average people there but with ourstanding endurance. And this motivates me more than just defeating someone on a race.