Little kids have it down. When I was a little kid, I would jump on my bike and ride and ride - Sometimes I was a confederate or Union soldier and my bike was a horse. Sometimes I would ride and see how many bugs I could squish. Sometimes I was a cowboy and the little girl next door was a cow (she didn't like that very much).

But I didn't know how much my bike weighed. I didn't have a HR monitor, or a computer. I didn't know anything about "aerobics".

The first bicycle ride that I did not enjoy was when the Boy Scouts made us do what they called a "Bike Hike". Set distance, lots of rules, frowning faces. All I could think about was when I get home I was going to get on my "horse" and chase bad guys out of the neighborhood.