Realizing you don't need an excuse to do what you like doing.

Taking a moment to relax and gaze at the stars or enjoy a coffee on your own just sitting there lost in thought is as good an activity as having a smoke. I really don't see people judging other people for it.

Or if you're actually looking for an activity not an excuse, just thinking about a interesting topic/problem and writing down the thoughts going through your head on your phone (or even better onto a piece of paper/notepad, no interruptions) can be an very satisfying activity I found out.

Really helps me to focus on whatever I'm thinking about too.

Easier said than done, but wake up an hour earlier and go for a run. Don't need to kill yourself, just go outside or to the gym or something.

Although it won't give the same social protection, chewing a gum is a ritual for me and helps me relax. I started this habit after seeing it on the show House of Cards and to my surprise it is really effective for me :).

I think you can always say that you need some fresh air and go out.

A non-smoking table. We have one at work.

It's mostly empty, though.

Vaping.

A book :)