Something movement patterns can get 'stuck' in your body. This can be due to habits. Your body moves daily in accordance to the demands that you put on it. As humans we sit too much and this can and usually does create stiff hips which then cascades throughout the whole body because if something is stiff then a compensation will be made somewhere else.
As babies we learned how to move our bodies in all the directions required for great locomotion such as rotation, moving forwards, backwards and sideways. Generally as a baby/young child these movement patterns will be perfect. If you get the chance to observe a baby/toddler watch now effortless they move. They squat and just bend in amazing ways that allow them to move with grace. Then this changes! We go to school, carry heavy bags, sit on chairs for hours, get emotional, make friends, lose friends....... all this lifestyle changes how you use your body.
As an adult all the growing up patterns and life stress have 'embedded' into movement patterns and then jobs come along meaning for 8 hours a day most of us have to do the same thing such as sitting at a desk. It almost 'breaks down' our amazing body unless we 'undo' all the sitting or other movements that we do. Without intervention then pain can begin.
It is NEVER too late to begin healing from stiffness, pain, stress, aches....