"Happiness is a way of life" might be a very distressing sentence for that kind of a person who never is happy to the current state, may it be because they are never satisfied or because they have trauma or something else that prevents them to be happy in that way that they could say that they are happy. For those people "Happiness is a way of life" sentence is a constant reminder for them gloating and underlining the fact that why can't they just decide to be happy. Just like someone might say to a depressed person that why can't they just stop being depressed and go out jogging or smile more or stupid stuff like that. For a person who can't be happy, the sentence might even make them more unhappy.

Happiness for me is that if I'm not happy, I try to change it if it's something I can change. If I can't change it, I whine and moan and complain about it until I'm totally fed up complaining about it, turn my attention to something else and move on. So looking back, the thing might still be there and not good but I've made it little enough issue in my brain so that it doesn't bother me anymore and I can say that mostly I am happy with what I got.