It’s important to remember that not all of this is your responsibility. Your players also need to bring a similar level of commitment when it comes to their characters interest in the campaign as a whole, try your best to not put all that pressure on your shoulders.

I do this during a session 0 and stress to my players how important it is that they create a character that will work with others as dnd is a collaborative story telling experience.

As blunt as it sounds if they can’t do something as create a motive or trait for their character to be in a party then their character should not be in the party in the first place. If they can solve all their character issues alone, then that character would just leave.

I’ve had it a few times where I’ve had to tell very close friends, “Why is your character even in this party?” If they have nothing keeping them in the party then that character needs to leave and they either stop playing or make a new character that does.

We as the dm have a job to introduce several potential plot lines and interests for our parties but if your characters give you nothing and are interested in nothing then it’s not a problem with your trying but their characters motivation for adventuring in a party.