Getting into a running habit? One of the first things you’ll want to know is exactly how many days per week you should be running. The answer depends on your goals, your schedule, and your body, and it’ll require some trial and error to figure out your magic number. I can personally attest to that: it took me about three years to realize that running four to five days a week was really not what my body wanted to be doing. (Now I’m down to two or three, which keeps my knees from completely hating me.) And while, yes, you’ll have to mess around with your schedule to see what works best for your unique body, there are a few rules of thumb to keep in mind when deciding how often to hit the pavement.