The more you force yourself to work out the details, the more you fall out of love with it and your characters.
For me personally, I've found its a matter of thinking about your characters in a positive way(much like treating a dog when it does a trick) and let them come to you, and with it comes their experiences.
I know that sounds silly but it worked for me, and i'm not saying it works for everyone as we're all different creatively
Thinking about my characters so much, I often get snippets of ideas in dreams and recently had my first revelation in the shower which literally solved every problem I had with my plot and fuelled even more ideas.
Now if you're really stuck, advice I would give is: choose a character, could be your protagonist, antagonist, support, heck even the family dog, it doesnt matter. write them into a situation, any situation. And youll soon find that the character will take the lead away from you, and often this can lead to some interesting stuff, not only to help you understand your character, but their motivations and desires
I hope this helps!
