Many of us spend an inordinate amount of time sitting in front of a computer all day, and as a result we end up with the movement quality of a sloth and our hips require a crowbar to unglue them. Perform this simple "flow-type" drill prior to your next deadlift or squat session. It covers many bases, including working both hip internal/external rotation, improving hip flexor length, and glute activation.
Shin Box Drill
If you struggle with the drill, you can make it easier by supporting your weight with your hands behind you throughout the set. As you gain more proficiency, however, the goal would be to do this drill without your hands.