dont generate anger so often you can.
dont supress your feeling.
dont express your feeling.
be with the reality as it is instead!
The short version:
There is what is called indifference, apathy, numbness. In this, there is no joy and no suffering, no happiness but no sadness either. This is how many people interpret Nibbana too -- as the numbness of experience. But it isn't. It's possible to develop such numbness, but that numbness is itself merely a subtle form of dukkha.
In the case of equanimity, there is joy. Not ecstatic joy, but tiny joy. Whereas in numbness is a subtle form of dukkha, equanimity is a subtle form of happiness. And whereas numbness is ignorance reborn, equanimity is associated with wisdom.
The longer version:
To understand equanimity, one must first understand real happiness. I actually do not think it is possible to truly know what equanimity is without at least attaining the first jhana. Perhaps that's wrong. It's just... Equanimity is built on top of the happiness born of mindfulness and morality.
It's like smelling the flowers, enjoying nature, a warm coffee or shower in the morning, the pleasant feel of a human touch -- all without delighting in them. One can be swept away by the simple joys and have ecstasy even over nature, then reality comes along to remind you of the first noble truth: suffering. One develops equanimity first by practicing mindfulness until one realizes the infinite happiness born of concentration, but then, seeing the danger of it, one practices restraint. Because the happier one is, the sadder one can become. So, you take that happiness born of concentration and you squeeze it, tighter and tighter, smaller and smaller. You squeeze it, because you know, "I love this happiness. I really do, but I know it's impermanent and notself. If I hold onto it and delight into it, it will eventually fade and I will be disappointed." So you make it smaller, so that the disappointment is smaller.
Eventually, you may come to a point where people wonder if you're even happy, because you don't seem to be. But you are. It's just a subtle form of happiness (and actually -- you're smiling all the time -- crying too, but they're tears of joy). But it is also supreme happiness because it stays with you, and doesn't come and go like the intoxication of drugs or the intoxication of delight in every day experience.

