Asalamualaikum, I want to know if in jannah one can live in fantasy world of their wish or fictional world. I need motivation but when I read about jannah I dont feel much motivation

I would advise that this is one of the bad results from getting attached to fantasy, whether it is through the influence of social media, literature, or video games. Imagine if we are not motivated to enter into a life where there is no death, no illness, and no sadness. Whatever you imagine and fantasize of these worlds doesn't even come close to the goodness that you will see in Jannah. If all of this does not encourage you, but what encourages you is just some fantasy idea, then there is a flaw. There is something blameworthy in your own character and your own self that you need to revisit and bring yourself into account and a strict advise like this in my opinion is a wake up call and a remedy.