Spatial Relations

What makes a distance a distance?

I mean, how do we know it takes, say, 2 miles to get to school, or 15 miles to get to work?

One can "feel" that some distances are greater than others. But some days, don't some distances "feel" shorter even though one's traveled them X number of times already?

One can "see" that one thing is further away than another. But this is merely a matter of immediate comparison which can change the moment you change your position.

One can "measure" distance by using instruments. The question remains: Does the machine correlate with how we "feel," or do we adjust our feelings to correlate to the measured distances?

Take for example, a 25 mile bike ride down the beach, in contrast to a 20 mile bike ride through hot, humid, industrial downtown.

Without an instrument to measure distances, would not these two distances, perhaps, via personal judgment, be swapped?

Also, we should remember that there is more than one way to get to the same point. The distance conventionally used to label two points' distance apart is not the shortest distance between them, for such a distance involves the curvature of the earth.