I thought high school was over?

Sometimes I think work is just high school grown up. I honestly feel like the only adult in a sea of 40 something co-workers. I have recently been promoted to nurse manager of the clinic I am at. Lets just say the clinic I am at was in big trouble with various issues before I got there and a lot of crap has been dumped for me to clean up. While the clinic is improving, my relationships with my coworkers struggle a bit. What happened to our Grandparent's generation of of suck it up and do the work? I love the Patient Care Techs that I work with but that being aside, they drive me crazy!!!!! You try to be fair, you split work evenly, you accommodate and nothing. All I get is complaints what makes one happy pisses off another. JUST SHUT UP AND DO THE JOB!!!