The Hub is a great place to do an alternative form of exercise. They have problems of many different kinds, ranging from beginner levels to very difficult ones. The good thing about this is that they change their problems every so often, so if you are bored of the ones up there, you only have to wait a few weeks before new ones are up. They also have so much climbing surface area that you can work on a separate wall each time you go.
They not only have bouldering problems, but they also have top-roping, yoga, and a work-out gym as well.
There's a great community of climbers here as well, and the staff are always friendly and helpful.