If your hips are feeling really stiff and achy, especially by the end of the day when you've been sitting or standing a lot, there's a really quick stretch you can do.
Cross your ankle over your knee and pull your knee towards the opposite shoulder. Hold your leg with your hands so the hip is relaxed.
Just a really gentle stretch under your hip is the only thing you should feel. Hold the stretch for 30 seconds, relax for just a second and repeat until you've spend a total of 2 minutes in the stretch position.