Find it hard to be myself in work

I like my job, people are nice. Ive always had this automatic barrier though with others. I know we all have our work face but it seems I'd enjoy it more if I was a little more open.

I guess I feel awkward about telling people about myself?. Maybe I don't have much in common.
I'm not a jokey person though I am nice and everyone likes me. I'm a different person outside of work but maybe that's normal?.

I have to focus a lot so it's not like I can just switch off and have a chat.