If we could only avoid three actions, life would be much happier. These are complaining, criticizing, and condemning. But it is very hard to do.
Complaining is always a result of dissatisfaction with something. The dissatisfaction essentially arises from not being able to accept what is and a desire to change it to what should be . Likes and dislikes are intrinsic not only to human nature but to all living organisms. What we like we want to continue, what we do not we want to change. But there are not many things that we can change. The only thing that we can control is our own attitude to things. The change of attitude takes care of all other changes.
The change in attitude involves altering one's thought process and the present is the only segment of time in which that can be done. At any moment of time there are a number of possible paths that an event can take. We cannot alter what has happened and is already in the past. But we can influence the path that events in future can select out of myriads of possible ones through our thought process. Thought translated into action can influence the outcome in the future and in that sense it is possible to change one's destiny. For this to happen though one has to control the mind instead of being controlled by it. Do not let it dwell on the past and dream about the future, but think and act in the present.
This is a reality which one has to accept in order to have inner peace and happiness. But most of us are unable to do this and we keep complaining. We complain about weather for example knowing full well that we cannot do anything about it. At times we complain against luck, which always pertains to things that have already happened and are in the past. In this case also we are full aware that it cannot be changed. As a starting point, though, we can learn to accept the facts and complaining would stop.
Criticizing is also like complaining but it is a more aggressive action. Criticism may be of a view or action toward which we adopt a rather belligerent approach. Most of the time it involves a lack of understanding of the other person's viewpoint. As long as there are different people there will be different opinions about things. Most of the conflicts in life or in the world arise because of this lack of understanding. In this respect the most serious are the differences in ideologies.
Condemning is criticism in its extreme form. It is a violent reaction to some action by a person or a group. It is usually a response of our conditioning determined by various factors such as social, religious, or even associative. In this case also there is a complete disconnect between the thinking of the condemning and the condemned parties. Each has its own interpretation (or idea) of right and wrong.
As stated earlier it is hard to refrain from resorting to these actions. However, if one starts to realize the futility of these actions in personal as well as social life, it may not be so difficult to make a start - not by just making a resolution but by acting on it.