Identify a door with ample space to exercise.
On the other side of the door, feed the door anchor through the hinge side of the door above or below the hinge depending on the height you want the harness.
On the other side, pull the loop through the door.
Once you have the adjusted the height, close the door to secure the loop.
Ensure the door is closed or locked before exercising.
Ensure the anchor is passed through the hinge side and no other side.
Ensure the door stop/threshold is on the side of the door that you exercise.
Attach the harness to the loop and begin exercising.