what can I do at my workplace during downtime?

my future job involves taking labor samples from point a to point b in a huge university campus involving several buildings and there is a ton of downtime: I often see my future coworkers playing on their phones, buying coffee several times a day, talking or smoking out of boredom.

There are moments when every laboratory wants you at once but even then they take it easy and a person cannot be at two places at the same time.

I don't know if it's really going to be this relaxed but it really looks so.

I was thinking loading my smartphone with books, find a quiet place and read, learn something.

Instead of smoking I could stretch and do some easy pilates and yoga.

there's always going several times to the toilet to have a seat and relax with nobody pestering you.

I don't reckon I could study something for college, write a book or poetry or learn a foreign language, as I couldn't concentrate.

what do you do in your downtime when you're lucky enough not to have a supervisor micromanaging you?