Do not eat when you do not crave what you are eating
I have been retired for six years and there's nothing left to rank that doesn't involve making a new account. That doesn't mean that I stop logging in though. For the most part, I just wander iria alone and stage fake screenshots so that they look like album photographs or I use mabinogi as a reference stage for hand drawn animation. It's easy to have fun alone in that sense.
That, or make friends; Close ones. Even if they themselves don't really 'play' the game either, having someone to talk to who still logs in is always +1 interest and a small tie to enjoy things with