Understanding the physical natural of time has been something that physicists have struggled with and debated over since before Einstein brought into mainstream scientific reasoning. It's difficult for those without a degree in physics to comprehend moving at different speeds based upon the relative position and speed of travel of the observer, but it's been proven time and time again (pun intended).
This video by Chuck Missler at Koinonia House breaks it down for us nicely. Rather than talking over the listener, he explains it in hypothetical and real world terms that won't put (most) people to sleep.
