Loving God is not for God's benefit, but for ours. Our emanating love towards our Creator helps us emanate compassion for all our fellow human beings. It is the Greatest Command(ment), and the sole purpose of religion.

As such -- as you say -- changing positions is good for our body which helps us to be more physically comfortable in this magnificent machine. Happiness is God's desire for us, but It has given us the absolutely free will to choose happiness or its opposites. A prayerful life is for personal and societal growth towards selfless compassion for all others, and away from selfish callous disregard for others.