Reflecting that the world is as it is the most important thing that you can do to develop Equanimity. Things are as they are. There is nothing in my opinion that's going to produce more understanding of life, in particular, and more Equanimity towards life than reflecting that things are as they are. You can't change it, in the sense of the overall world as it is. Illness, decay, old age, death, all these things naturally occur. Separation from things that we like, having to be with things we don't like, these things all naturally occur. To see things as they are is very important.
Now, how can I cultivate Equanimity besides this? Reflect on the Dukkha of not accepting the world as it is. Just reflect on it, look at it in your own life, how many times have you rejected things as they are? What did it give you? It gave you Dukkha. The more you reflect on the Dukkha of not accepting life as it is then you will come to more of an appreciation that "Yes, indeed, you must accept life is as it is."
You can also reflect about Kamma, the Law of Kamma exists. When a Buddhist person has a loved one who dies and they reflect, well, it's the loved one's own Kamma, they were supposed to die at this time. It's my Kamma that I'm supposed to have a loved one who dies at this time. Then a person can have Equanimity in that way.
So when you look at people who are having Dukkha from not accepting and you look at yourself when you have Dukkha, when you don't accept life as it is, then that in itself can lead you to acknowledge that this is not the right way to go.
Not only can you look at life as it is and work towards developing the understanding, "Yes, life is as it is," but you can also look at what happens when you reject life as it is and how much Dukkha you get. By and large the more we understand about Dukkha, where it comes from, then the more we can work towards stopping the causes that bring it about. If you can see more and more that when you don't have equanimity, that you create your own Dukkha, then that in itself will encourage you to develop more Equanimity.