The faster you walk, the quicker you'll get there, it's true. But be warned, it's not without a price, for the faster you go, the further you'll have to walk before you arrive.
This could work:
You're meeting a friend walking towards you (replace friend by anything that travels in your direction : bus, train etc...). The faster you go, the further you'll meet him, albeit quicker.
Alternatively (with the same reasoning):
You're walking on a conveying belt.