Eventually, the terrain levels up.

Maybe there's another hill.
There might be rocks on the path.
Maybe the angle of descent is too steep.
Maybe you'll need to adjust your weight.
What if you put your arms out?
What if you slip and fall?
What if you trip?

I like hiking because it slows down the mind.
I especially like hiking up and down hills.  

Why?

Because if you take your mind off what you're doing in-the-moment, you're sure to trip. There's no time for second-guessing, thinking too far ahead, or behind - there's only the moment in front of you. 

The minute you start thinking too far ahead, or too far behind, is the minute. And, nature has a funny way of keeping you in check.

Consider a hike.