Many of the CSU campuses are based very close to the countryside, offering rural escapes from the pressures of academia. Though the public transport connections may not always be the most reliable, the beautiful surroundings make for brilliant trails and bike rides, and the fitness facilities are numerous and well-run.
Clubs of all kinds exist to facilitate strong inter-student relationships; some are course-based, religion-based, musical, sporting, etc. The sports teams in particular are a great way to combine exercise with social activity, so if rugby, sailing, swimming, golf, fencing, and many other sports excite you, then these clubs are exactly for you.
Since there are so many campuses that are under the umbrella of CSU, I suggest reading into which campus has the lifestyle that suits you as an individual.