It's a tricky thing, rage is.
I think that in life things do tend to build-up inside you - an inevitable consequence of living in this day and age. It can't be avoided.
But it doesn't necessarily mean one will always keep ending up in a rage. The trick is to have regular things in your life which serve to comfort/soothe/pacify/etc, and that act as healthy emotional outlets. Doing these things every day is the ideal. If you don't, then the danger is that a rage-attack/s may result, at some point. Particular difficulty can arise from certain experiences in life (depending on the individual) - these can "get the ball rolling" quite quickly, which can very easily lead to rage if you haven't been "looking after yourself" (in my experience).
Also, environmental toxins, as well as diet, can also play a very key role in the triggering of rage.
So basically, I think the golden rule is to "look after yourself", and try not to let unexpressed problems/thoughts/feelings build up inside. Easier said than done, but I believe it's a life skill any person can learn.