It doesn't have to be 5 miles of non-stop running, or even 3 miles.
It can be as little as 1.5 to 2 miles. As long as you DON'T STOP from point A to point B and can hold it for at least 15 to 20 minutes your body will release endorphins and you will immediately feel better for about a couple of hours.
Not to mention that confidence you will feel (running is hard) from going from that Point A to Point B without stopping and pushing through the pain.
It can be as little as 1.5 to 2 miles. As long as you DON'T STOP from point A to point B and can hold it for at least 15 to 20 minutes your body will release endorphins and you will immediately feel better for about a couple of hours.
Not to mention that confidence you will feel (running is hard) from going from that Point A to Point B without stopping and pushing through the pain.