Of course, you can complain a lot if you want. “Complain once” is just an idea you can contemplate. Reflect on it. The reflection may go a lot deeper if you have a strong awareness practice which is sitting down, holding, still, and watching the movement of the mind. If you don’t do this, you will believe your thoughts. You will believe your emotions. It is not that they’re not there, it’s just that they are not true. They are relatively true but ultimately not true. If you don’t understand what that is, you should check it out!
https://www.youtube.com/watch?v=SK41cieaSdo&t=2s