Complaining is a bad habit, and like any bad habit, it can be changed with discipline and perseverance. Complaining is the activity of people who feel powerless. Notice I say "feel" NOT "are." Have you ever considered doing something to change the situation you are complaining about? Action removes the sense of powerlessness. And action usually involves changing something in ourselves. It requires insight into our perceptions, our fears that block us from changing. Complaining is an ANGRY energy. It is passive-aggressive. What if you were to tune in to that energy as pure sensation, without judgment, and use it to mobilize the action necessary to create the change? After all, all emotion is just that "e-motion" = energy in motion. Move the energy instead of being stuck in the quicksand of complaining. That will only create misery, instead of the opposite of what you are complaining about. How about when your complaining is about other people's behaviors? You cannot change other people. It is an impossibility. You can only change yourself. So what then? You still have options: 1) change your perception of the person; 2) accept the person exactly as they are; 3) do not have a relationship with the person ... and so on and so forth.
