[hereonbusiness]

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.