Well, most of us work the hip flexors (including the psoas and iliacus) most of the time- sitting, practicing while seated, cycling, driving...but only in a limited range, i.e. knees and hips bent to 90 degrees. We need to balance out the movements of the hips a bit more- add more extension and more varieties of flexion. For example, sitting cross legged, sitting on the floor, squatting, kneeling, etc. all require more varieties of hip movement. To get more hip extension in your life, you can add some restorative exercises like standing apanasana, lunges (lots of lunges!) and go walk (not on a treadmill). That way, you don't lose your capacity to move those joints to their full capacity, and you will have loaded the tissues in more diverse ways.
Your skeletal, smooth and cardiac muscles work together to keep your body running like a machine. Within this muscular system there are various parts, from muscle fibers to ligaments. You may know about hamstrings, quadriceps and abdominal muscles, but there hundreds of muscles that move within your body. Some are involuntary, like parts of your digestive system, while you control others whenever you go for a walk or lift weights.
Last month, I talked about the unique complexity of the shoulder, and how a problem there can produce effects throughout the upper body. Well, the hips are just as complicated, and pelvic dysfunction can be just as far-reaching. Your erectors, glutes, hamstrings, abdominals, quadriceps, hip flexors, and more all interact at this junction, and a problem with any one of them can lead to debilitating immobility and weakness in lifting and in life.
Tight hip flexors can also make it harder for your glutes to activate—since they're opposing muscle groups, when one is really tight the other becomes lengthened. When a muscle is more lengthened than it should be, it takes away some of its ability to contract. When your glutes are in this compromised position, it can cause other muscles to do more work than they should, making your workouts less efficient and sometimes, increasing your risk of injury.