People have one of three responses to a tense situation.
Aggressive - shouting, waving limbs, hitting, swearing, trying to start a fight
Passive - trying not to react, lowering head, going quiet, trying to keep peace
Assertive - Discussing, stating wishes and needs, trying to resolve the situation.
Out of all the approaches listed about, I think the passive approach has to be the most detrimental to one's mental health. How can your needs be met if nobody knows what they are?
The Assertive approach can prevent build up of resentment, and can also help to prevent a violent outburst. You state your needs, you state what you would ideally like to happen, and then if that isn't acceptable to the other party, you compromise. You are not then left with (passive) the feeling that you should have spoken up of (aggressive) the feeling that you have over reacted.
As our children get older I think it's important to be assertive with them, as being passive will get you walked all over and leave them with no firm sense of other people's rights, and being aggressive could leave them frightened, and with no sense of their own rights.