Looking for a word that describes a way of thinking

I'm looking for 1 word preferably that sums up this ideology.

I believe that bad things that happen to you are not necessarily bad, in fact using the yin and yang theory or you can't have ups without downs and vice versa.

For example: being grateful that you grew up poor because you will appreciate your riches when you get them, or in extreme cases deaths of close relatives, even your parents, can be good because it can make you a stronger individual and more motivated to succeed for them.

Solution 1:

Synthetic happiness

May not be what you're looking, but was the first thing that popped into my head.

From the TED speech by Daniel Gilbert:

Natural happiness is what we get when we get what we wanted, and synthetic happiness is what we make when we don't get what we wanted.

It is about accepting what you have been given, without choice, and being happy for what you do have. When you come to conclusion that you cannot change the past you synthesize happiness.

When having the belief that you can choose to change the situation or reverse bad events it becomes a roadblock to synthesizing happiness.

Solution 2:

KannE mentioned Pollyannaism in a comment.

To explain, referring to Merriam Webster ([1], [2]): Pollyannaism is derived from the name of the character Pollyanna, from the eponymous novel ((1913) by Eleanor Porter), and is a person who finds good in everything, and has unfailing optimism.