Ever wonder why you feel so good after working out? It’s not just your imagination at play – psychologists and exercise physiologists have found that exercise may actually work as well as drugs for treating depression.

A Duke University study tested this theory by recruiting 156 men and women age 50 and older who suffered from major depression.

They split the study participants into two groups. One group walked or jogged for 30 minutes three days a week, while another group simply took the antidepressant Zoloft.

At the end of four months, both groups improved dramatically. But the real surprise came when the researchers checked back in with the participants six months later. Thirty-eight percent of the Zoloft group had fallen back into depression, compared with only 8% of the exercise group.

So I say, when you’re feeling blue, just throw on your walking shoes!