Are you standing up? Try raising one arm up above your head; how easy did you find this?
Now feel your feet on the ground and imagine that the movement is beginning from there, passing up through your body, along the arm and flowing out through your fingers. Does this feel different? Did your arm move further? Compare the two ways of approaching raising your arm again. Use the hand that is not moving to feel what is happening with the rib cage on the lifting side.
If you felt both ways were equally easy you may be one of those people with intuitive understanding of where movement is generated and how it travels through the body. For many people, moving the arm often involves an isolated movement relying on the upper shoulder girdle muscles and recruiting in extra help from the neck. Shifting this to a movement where more of the body is invited to join in allows the body to free up as well as share the effort, allowing the arm to move further and with more ease.
Now play with your posture. Allow yourself into that slump that we see so much of; try raising your arm. Let it back down and imaging your spine lengthening upwards and up out the crown of your head, supported by a helium balloon. Your shoulders are left behind, nicely relaxed. What happens when you raise your arm now? Experiment with tensing your jaw and seeing how that changes the movement. and then again with tensing up your neck muscles.
We often see this full body movement in sport; a tennis player uses their whole body to generate the power and control that begins in the feet and legs, travels up through the pelvis to the middle of the body and on to the shoulder and emerges through the arm into contact between racket and ball, whilst a footballer's upper body and arms will be working just as hard as their legs to kick that ball.
Allowing our bodies to find a position of ease from which to initiate movement and allow that movement impulse to travel through the body and out can make it all so much easier once we can find a way for our bodies to rediscover this knowledge.