Your psoas needs to relax and be let go of, in order to be happy and dynamic. This will give your body greater resiliance. Therefore, this is not a muscle pumping exercise, it's a muscle/deep tissue awareness exercise …
1. Use a yoga mat or something similar. Lie on it with your back down.
2. Let your feet rest on the floor, with approximately the size of your fist in open space between them, your knees at about a 45-degrees angle. This should make your hip bones (femurs) rest nicely into the hip sockets, allowing your psoas to rest down towards the spine and floor.
There's also another way of doing this: Pull one bent leg at a time up towards your chest. Letting your foot drop sloooowly (!!!) down towards the floor, sensing its weight all the time. When you've landed both feet, make sure to adjust to the fist-sized space between them to allow proper alignment from foot via knee to hip joint. The idea behind this way of doing it is to let each psoas decide how far away from your hip the foot should be, because each psoas usually have a different tone. This worked for me in the beginning, but now my psoas can sometimes be too supple for correct positioning. My feet sometimes end up right next to my butt, preventing the femurs to gently rest on top of the joint.
3. Place both thumbs on your belly-button, and stretch the fingers like a fan opening towards your hips and pubic bone. This is so that you can get a more physical experience of where your hip joint is. Consult a picture of the bone structure of your hip joint for more clarity.
4. Eyes open or shut, picture your bones. Your pelvis, your entire spine (one vertebra at a time), the rib cage and skull. Take good time doing this. Feel your own weight on the floor. "Where do I feel my weight the most?" "Where do I feel my weight the least?"
Imagine/picture your psoas. From the inside of your upper thigh bone (the lesser trocanter), the psoas runs over your ball-and-socket joint of the hip. Through the entire pelvis, it stretches up to each of the five lumbar vertebrae and even to the last thoracic vertebrae, connecting to each of their lateral sides. All the time, feel how soft and warm the psoas can be. Exploring how much you can give it to gravity. Imagine it being revived with fresh and healthy blood. Feel your intestines, your organs. Is there much space for your psoas, or is there less? All the time keeping an inquisitive alertness, open to your core awareness. If emotions or energies or even motoric movement appears, let it do so. This is an exercise in how to allow your body to be exactly where it is at, not forcing it into a shape or condition. Simply loving it. And if it is hard to do, allow that too. You are only observing, letting go. The quickest way of having even just a small part of your psoas relax is to open and let go of your hip joint. Not with movement, but with awareness. Just let your ball-and-socket joint be heavy, open, relaxed.
When you've done one side, do the other, then do both, or do both from the beginning. Whatever comes naturally and easy to you =)
5. When you feel done, slowly and dynamically let your weight shift to your right side, and lie in fetal position for a minute, letting your nervous system adjust to this new, revitalized core. Use your left hand, and then your right, to push up into sitting, continuing alertness. Does this feel different to before you did the exercise? When you're ready, stand up (slowly). What's new?
You can do this exercise alone or with someone helping you, saying the steps to you, and playing with your inner awareness.
I've instructed a few musicians in this exercise, and they got incredibly grounded, filling the room with presence and healing energy. Enjoy!