Every
person,
thing,
particle is always moving at the
speed of light within spacetime (for
us it will suffice to have one
time dimension and three
space dimensions). When we are at rest, the entirety of our speed is in the time direction. When we then move in one or more spatial directions, part of our speed is required to move in the new direction and therefore our speed in the time direction is reduced. (If our
velocity vector doesn't lie entirely on
time axis then the sum of the
time vector and the
spatial vector will be our
velocity vetor)
What all this explains is just that "folding" of space and time into one. This explains why, for example, when something travels at the speed of light that time for them ceases to pass. (The entire velocity vector whose magnitude is always equal to c (see above) then is in a spatial direction and there is none remaining for the time direction.)
I find this explanation to be very helpful in understanding the relationship of the space and time. And I like to think that I'm travelling at the speed of light, even as I sit here on my bum....
Concept from The Elegant Universe by Brian Greene