IMO, we would have to begin by examining our selves and our early childhood to understand where our attitudes come from and why we have them. Many 0f my attitudes were programed into me as a little, defenseless kid (just as they were into my parents and their parents, etc.) and it has helped me to change my attitudes by first examining the ones I habitually use and deciding which ones I will keep and which ones I will DUMP from now on. It's interesting to notice how difficult it is to dump unwanted attitudes and behaviors that were installed in me years ago and that I have unwittingly obeyed all these years. I'd guess most ppl never question their automatic behaviors/feelings and just go with what they were taught (programed) in childhood. Once these automatic/scripted attitudes are examined, we might be able to employ "proper attitudes towards external events." As Epictetus recommends. Owing to my very dysfunctional family background, I find that most of my attitudes are not good and so I am constantly trying to undo past mental damages and adopt better attitudes - once I learn them!
IMO, the problem with simplistic recipes like Epictetus offers is that they do not include significant elements such as early childhood conditioning and ramble on and on as if everyone is perfectly healthy and well suited to adopt his simplistic concepts. Well, maybe if someone tries to use "proper attitudes", they might realize that they will FIRST need to repair the wrong/bad attitudes they already have from childhood and start over again.
All of human behavior needs to be examined from the ground up (early childhood influences) before someone can offer these simplistic recipes for good behavior. If you had unhealthy beginnings, you are most likely NOT going to be able to summon up "proper" attitudes in any situation.