It is also relative to how much you earn as well. When you are on a tight budget 45% of your wage is a lot. In fact 20% of a low wage is a huge chunck out of your pay.
We paid 45% of our income in rent last year however it wasn't too bad. We still had enough left over to live a comfortable life. When we were younger and on lower wages I remember only paying 15% in rent and we struggled a lot even on that.