However, in a normal working relationship, a good leader will not order people to do things, but will ask. When you ask people to do something, explain why. Assume that they are interested and intelligent. Show how the job is important. Build up the feeling of importance and satisfaction they'll get out of doing it well.
Some people actually love to gripe.
They feel a psychological need to criticize. The best way to handle gripes is simply to listen patiently and attentively. Be receptive and appreciative. Being a good leader takes a rugged constitution. One comes face to face with some pretty discouraging facts about human nature.