Sometimes if you have a lot of tension in your head, it's helpful to drop your awareness down and just feel the buttocks on the pillow for a moment, just relax into the touch of the buttocks on the pillow.
Sometimes we get stressed in the head because we're trying to control the breathing. We're trying to make it a certain way rather than just watching it as it is. Many times people have ideals of how the breath should be and then they try to impose it on the breath. But if you've had a busy life, your breath may be short. That's okay. We don't have to have a long or "relaxed" breath. You'll only create more stress if you're trying to force the breath to be other than it is. In many ways you have to develop more compassionate awareness. Sometimes we're trying too much, so it's important to learn how to relax down into the buttocks, feel the buttocks on the pillow or the mat; relax into this because you can't control that touch. It just is. After you're relaxed, then bring your awareness to the body and try to feel the breath wherever it is.
Also, you could bring your awareness to the out-breath. Sometimes we have a strong in-breath, and we're holding the breath, trying to make it a certain way. So watch the out-breath first and try to find the particular area that is most comfortable, perhaps in the body or in the nose area, but in a very relaxed, easy way.
We talk about our awareness of the breath being like an elephant, where we're trying to overpower the breath, or like a butterfly where we're just resting on the breath. Try to make the awareness like a butterfly, just observing whatever it is. If it's rough, if it's short, if it's long, if it's even agitated, it's okay. As we bring more objective awareness to whatever is, then that objective awareness allows the breath to change because everything is interconnected. If there's more effort and more "me" in our awareness, then you'll be influencing the breath. If there's less of the "I" doing and more of just observing what is, whatever it is, then it allows the awareness to become more gentle and some of the stress in the body or, especially, in the head may start to dissipate. But that's not our purpose. Our purpose is to be aware of reality.