How about a Friday afternoon bouldering session @ BRIGHT SITE?
It doesn't matter if you are a beginner or a pro, all levels are very welcome and there're enough routes & add-on equipment for different preferences - just for fun, strength, balance, endurance, technique drills, etc. pp...there's also an outdoor bouldering area and 5 different slacklines at hand...
Regular entry is 10€ / students 8€ / if you have an Urban Sports Card >=M it's free for you. Pls bring your own padlock in case you wanna use the locker, shoes & chalk you can rent at place.