Seriously - when I was a kid and just rode the old BMX around the neighborhood it was enough to hose it down every year or two, then douse the parts in some WD-40.

When I started cycling more as an adult I quickly realized that I needed to learn how to maintain my bike (and that WD-40 is no good). Now, I spend so much time keeping the bike tuned and running smooth. All the drive components, tires and brakes need constant upkeep and replacement.