If you're looking to get in shape this year then one of the cheapest and easiest ways to get started is to get up and go for a run. Everyone probably remembers running the mile in middle school and high school and unless you had already started loving running, you probably found the whole thing a bit of an ordeal. But I promise, it's much better now when you're not getting graded or being yelled at to "Hustle!" from your teacher.
Throw on your gym shoes/sneakers/whatever you've got and take a jaunt around the campus. If you end up liking it and think you'll run more than once a week, it's really worth the investment for a good pair of shoes. They can save you tons in doctor's visits and injuries. Be sure to start by keeping your breathing as even as possible and if you start to get tired, go for the classic "inhale through your nose, exhale through your mouth". This can also help ease some muscle pain that might pop up if it's been a while since you've pounded the pavement. Don't be afraid to take breaks when you need to. Whether you're running or walking, you're still getting those miles in.
Stretching is good to do before and after a run, just make sure your doing dynamic stretches (which means that you're moving, not just statically holding a position). You can check out some ideas for how to warm up for a run here.
If you need a bit of a distraction, plug in your headphones and toss on an upbeat playlist that will help you keep your pace at the level you want. If you use Spotify, they have a "Running" option that will help you set your pace and play music that will keep you at it.
Now if you're going to be running or working out more regularly, you're going to need to some new threads. Check out the University Store for some great Sonoma State athletic gear for whatever your favorite workout is this year!