how to reattain khushu in prayer

Can someone give advice or at least send sources?

I used to always have so much khushu, at the time I still didn't think i have enough.

Now i can never get it

I can't focus in prayer and I don't know why but recently I have had an extreme dislike in being emotional in prayer, it is too burdening. Sounds dumb, could be whispers. It feels weird to connect in prayer now.. I have never been an open and mushy person.. It makes me uncomfortable. But no matter what, even though I disliked being mushy and opening up to others, I still did do that in prayer. But now I cannot anymore. Even when I repent, I have the ability to put morre heart into it but I do not like to do so. I still make a genuine change to stop the sins though. There must be some kind of disease of the heart. Is this a lack of humility? I still acknowledge that I am a slave of Allah and that I must obey Him

but on top of that, I rush my prayers because i dont enjoy them anymore and I don't have the will to enjoy them for some reason.

I think this is why it has been taking much more effort for me to hold back from sin.