It doesn’t say that those heading for eternal life do not have some preparation to do.
I think it is perfectly obvious in my own case that while I do want to hand my life over to God and I am sick and tired of my habitual self-centeredness, that I’m still not currently fit to be lived with for eternity. I can foresee that giving up what I will have to give up in order to be fit for heaven will be both painful and a great and joyful relief.
Either there is a Purgatory, a process of amendment, purgation, and formation which the nature of our self-centeredness will make painful, or there are very very few people who are going to see Heaven. Hell is for those who value their self-centeredness above all else, who will not let it go. By God’s mercy, may we be spared that fate. OK, then…we have to be ready to endure what it takes to be spared it.
I think Purgatory will be painful. I think it will be the sort of pains that one would not trade for any earthly pleasure, like the pains of childbirth, like growth pains, like the pain of stretching and extending the body to greater fitness. I DON’T believe it has anything to do with some sort of arbitrary punitive punishment that God feels some need to dole out. I believe that God will make Purgatory as painless as possible. There are some processes, though, that cannot be reached via numbness. After all, it is our numbness to sin, our insensitivity to the pains of others, that has to be cured. To be numb to sin is to be numb to grace, too. Purgatory must require losing our habitual state of anesthesia. That is why it is gonna hurt.
The obvious distance between what I am and what I would be, were I a saint fit for Heaven’s bliss, gives reason to embrace the painful process of accepting and embracing sanctity right now. God will make you into a saint, if you but yield to it. There is no reason to keeping Him waiting around to get started. But you have to count the cost, first. If you’re not willing to do it even when it becomes painful, it is better not to start.