> there is not enough "space" for that at work
It sounds like you are over generalising from a limited set of experiences.
> reflect on why it's so hard to come up with something alternative
Same with this one. I for one find it easy to talk about things other than my work, but also find it that people enjoy when I tell them about my field and have a ton of questions.
The key is to live an interesting life and be a good story teller. These are both things which can be improved on step by step if that is your desire.