If you were moving away from Earth at nearly lightspeed without acceleration, according to Einstein's special theory of relativity, would you notice any change in your pulse? Any change in your breathing rate? Anything unusual about your clocks? Why? (Note: explain why, pls.)
The short answer is no.
You will not notice any change in any of the physical quantities that are moving with you in your rest frame.
Special relativity principle is that one can not tell if hisher system of reference is at rest or is moving with respect to a "universal resting ...
In a 200 word cited solution, the questions are fully answered.