If general relativity says that velocities only exist relative to other objects, then why if I circle the Earth, am I the object that ages slower? Shouldn't my circling the Earth mean that the Earth is circling around me equally? If fact, any motion I make should be indistinguishable from the entire universe moving "round me, while I'm completely still. I never understood this as presented by Einstein popularizers. They make it seem that there is no concrete coordinates to the universe, but if I'm accelerating towards the speed of light, and I feel the effects of this, that means I must be the one moving against the universal coordinates, rather than me forcing the universe to move around me. Am I missing something?