A vague question about human nature/pain/and happiness?

No matter how miserable we may be because of the things we cannot control, we still go on living. In some moments, our misery disappears and those things become insignificant. Sometimes those things seem like they may never matter ever again. But eventually they catch up to us. They knock on the doors of our hearts and like fools we invite them in so that they may rummage through our most personal belongings and tear them apart. Why? It’s so easy sometimes, to let pain take ahold. Is it not just as easy to let happiness make itself at home?