Train in Amsterdam, Utrecht or The Hague without signing up for a membership.
A dagpas is easy to find in Dutch cities, with Amsterdam, Utrecht, The Hague, Rotterdam and Groningen well covered and Basic-Fit clubs among them alongside CrossFit boxes and independent gyms.
The terms differ widely: some clubs sell a single visit at the desk, others only through an app or with a reservation, and CrossFit boxes often sell a drop-in class rather than open gym time. Check the price, the hours it is valid and whether it includes classes.