No one likes to confess. Confessing means there was some wrong, some violation - perhaps a sin of some sort. It also means that there is some reason to take ownership of that wrong. It also means that the ownership of that wrong is communicated to some other. Confession is difficult because it makes vulnerable the confessor.
Sometimes confession is repugnant to people because sometimes confession is forced. It is the outcome of oppressive acts perpetrated by the powerful. Even if there is some genuine desire to draw out some genuine sense of contriteness, such an outcome cannot be forced. Forced confession, even if it is a true telling of the wrongs, is contrived contriteness.
Some people view confession like self-harm, like spiritual cutting. Why in the world would a person do that to themselves? Others view confession as some sort of exhibitionism - a desperate move for attention. And to be sure, there are some people who share their darkest secrets for these purposes, but these people are not actually confessing. There are a variety of things they may be doing, but confession, in these cases, is not one of them.
So, where is this "joy" in confession?
The joy in confession comes in the relief felt in taking a secret from inside and setting it on the outside, into a social context of you and another who loves you no matter what. Two can bear the weight of the sin more than one. When confession is a discipline, a common thing, the practice of the day or week, it loses its fearful anticipation of what bad thing might happen in confession and turns into the desired process that provides so much relief of holding in anything for too long.
When confession is a frequent discipline, it functions like other normal part of the day - exhaling, going to sleep, going to the bathroom, perhaps sneezing. In the discipline of confession, there is no sense to be made of waiting for some big infraction or for the minor infractions to accumulate to a critical mass. Daily confession is spiritual health like exercise is the body.