I can think of many good reasons to open up those hips. But, if you are like me that’s easier said than done. I have a tendency to sit too much, which contributes to tension in my hips (among other things). I have learned how to reduce this tension with massage and stretching through yoga. There are so many yoga poses that are great for relieving tension in your hips, but here are just two of my favorites which are good beginner stretches.
Butterfly pose to relieve hip tension
Begin by sitting on the floor with your knees bent outward and the soles of your feet pressed together. This is similar to a cross-legged position, but instead of folding your ankles over each other your feet are pressed together, similar to how you might press 
the palms of your hands together in a prayer position. You should be sitting tall with your back straight and your sit bones pressed firmly into the floor. You can sit on a yoga mat or on your carpet at home, but if this is uncomfortable feel free to add a folded towel or blanket for better cushioning (you can also add rolled up towels under each knee for additional support and cushioning).
Grab a hold of your feet or ankles with both hands and try to pull your heels closer to your torso, sliding them along the floor slowly so you can easily stop if you feel too much tension. I try to bring my feet close enough so I can grab each one firmly with my hands while sitting with a straight back, not hunching over at all. However, it is important for you to listen to your body and only go as far as is comfortable. Typically in butterfly pose you grab the top of each foot with each hand with thumbs on the inside soles and gently tilt so that you are in a sense opening your feet up like a book. This is to help push your knees outward and down towards the floor. But don’t expect your knees to lay completely flat against the floor, just let them fall wherever they are comfortable.
Just this position of sitting straight with your knees bent and feet together may be enough of a stretch in your hips. But, if you are able to take the pose further without discomfort, slowly lean forward over your heels, using your elbows to help keep your knees in place. Only bend forward as much as does not cause pain. You should feel a deep stretch in your hips but you don’t want to overdo it. Try to hold the stretch for five breaths, but hold longer or shorter depending on what feels best. Definitely do not “bounce” in the stretch as this can cause injury; it should be a slow, gentle movement. I recommend taking this stretch very slow—don’t push yourself too far too soon. You may feel some soreness or pain in your hips the following day, so it’s best to go easy until you know how your body will react.
Lunge on the knees pose to relieve hip tension
This is one that my physical therapist specifically recommended and I have really noticed a difference in my pain levels when I do this pose on a regular basis. For the purpose of releasing the tension in your hips, I only recommend this as a supported pose. I use the edge of my bed as support, but you can use a couch, chair, or pretty much anything that is the right height and solid enough to hold your weight. You will want to do this on a yoga mat (possibly folded over for more cushioning), your carpet, or with a towel folded under your knee.
Start by kneeling on one knee with your other knee bent at a 90 degree angle over your ankle. There should be a straight line from your knee on the floor up your torso, keeping good posture. Imagine the stereotypical proposal where the guy gets down on one knee to pop the proverbial question—that’s the pose we are aiming for here. I keep my bed (as my support) on the side that my knee is forward and opposite the side of my knee that is on the ground. This allows me to lean into the bed to help deepen the stretch slightly.
The most important part of this pose is to maintain good posture with your tailbone tucked and your pelvis slightly tilted. You can practice this standing sideways in front of a mirror. Stand fully relaxed and look at the sway in your back and down the curve of your buttocks. Then watch closely as you focus on correcting your posture by tucking your tailbone (like a dog tucks its tail) and tilting your pelvis backward.* The best way I have found to do this is by focusing on my lower abdominal muscles, the area between my belly button and mons pubis (or basically my pubic hairline). As I focus on tightening that band of muscles, bringing them inward and upward, I can see how my posture shifts. The sway in my low back becomes less pronounced and the curve over the top of my buttocks shifts slightly lower. It is a very small movement so you’re likely to not even notice it unless you are watching in a mirror.
Depending on how tight your hips are, you will likely feel the stretch just by correcting your posture in this lunge position. I typically feel the stretch not only in my hips, but also down the front inside of my thigh. A slight stretch is enough, so listen to your body and only stretch as far or as long as feels good. I typically rest one hand on my bed, grabbing a hold of the comforter for additional support to keep my balance. You can rest your other hand on your bent knee, or I typically grab the corner of my bed’s footboard which helps deepen the stretch slightly while also providing me more stability and support. You can scoot your forward foot slightly farther away from your knee that is on the floor to deepen the stretch, but do so carefully (and don’t allow your knee to reach past your ankle). Always check your posture before doing some other movement to deepen the stretch. Chances are you do not have your pelvis properly tilted which is why you are not feeling the stretch. And, of course, don’t forget to switch sides to do the same pose for the same length of time on the opposite hip.
As always, I recommend you discuss these poses with your physical therapist or yoga instructor, and never do anything that causes pain! I have personally found these poses very helpful in reducing tension in my hips and preventing flares in referred pain caused by tight hips. It is also important to avoid sitting for long periods. If you have to sit for work, try to get up and take a short walk around the room as often as you can (my physical therapist tells me to get up every 30 minutes). I hope these poses can be a help to you as you learn to open up those hips!
*I never know which way is tilted backward versus forward, so let me explain what I mean. If you were to imagine a line drawn from back to front (buttocks to lower abdominal muscles) parallel to the floor, the front tip of that line would move up while the back would move down when you tilt your pelvis backward for proper posture.
**Photo for butterfly pose was taken from http://blog.juil.com/2013/12/10/four-best-yoga-poses-feet. Photo for lunge on the knees pose was taken from http://yogateachercentral.com/blog/spring-memorial-day-sun-salutes/.