If your are unhappy you better check if one or all of these are lacking: Tapa (penance), Vairagya (dispassion), Sharanagati (surrender).
- Tapas is agreeing with the moment, total acceptance of pleasant or unpleasant situations.
- Vairagya means I want nothing and I am nothing.
- Sharanagati is "I am here for You, for Your joy."
If you are grumbling then these are lacking, because when you accept the situation you cannot grumble; when you take it as Tapa you will not grumble; when you come from a state dispassion ("I don't want anything") you don't grumble; and if you are surrendered you will have no complaints.
All these three (Tapas, Vairagya and surrender) purify your mind and uplift you in joy.
If you don? do it willingly you will do it in desperation. First you say, "Nothing can be done." Then in anger and desperation you say, "I give up, I want nothing, I have no choice, to hell with it!"