I have a friend, a fellow trainer/consultant. He is always complaining about everything. He complains about the consulting work he is doing. He complains about the very students he is training. And so much that I wonder why he is doing the training/consulting gig full-time like me as it seems he doesn't very much like the work.
I love my work. It's not easy. Things are not perfect. I come across difficult clients. I get students that won't get along easily. Still, I love my work. I smile at everyone I deal with. I even develop a liking for them for the sake of the work. I treat them nicely throughout the course of my work. I make sure they get that warm nice-to-do-business-with-you feeling.
Even when I was in a paid employment, I tried to love my work. To the extent of trying to get along nicely with impossible people so I can do my work well and end each day nicely.
Work fills a large portion of our lives. We spend the most of our active life at work, it makes no sense to go through it kicking, cursing and fighting. Either you find the work you love or love the one you have.
There are some people who believe growth can only come from discontent. They try not to feel comfortable anywhere, and take it as far as fighting colleagues and never feeling happy with their work. It is a wrong way to pursue growth. Rather than making things worse at work so you can be forced to look for something better, why not have a personal and career development plan you follow thoroughly that does not involve making enemies.
Altogether, what I'm saying is: regardless of the work you work, love it. At least, try to.