Hills (by which I mean "Slight Inclines")

It's interesting how you notice teeny slight hills when you're running. I have always thought of my neighborhood as an extremely flat place (which it is). But, when running I have noticed that there are actually slight inclines depending which way you go. I can run down my street and it's basically totally flat the whole way. Or, I can go up and down side streets, which have a slight incline. It's amazing how much harder the "uphill" is and how much easier the "downhill" is! What a difference a few degrees makes. :) My housemate Jessie, who just started biking, says she has noticed the same thing on her bike--that she notices slight inclines that she'd never thought about before.