Shifting in an automatic

In my auto 2006 Prerunner, I sometimes find myself shifting just for a more enjoyable ride. I know there's really no mpg difference, but it keeps me alert.

I was wondering, is there any harm in driving like this? I am taking a truck with 180k miles, and never a mechanical problem to higher RPM's, and don't want to push my luck. Any feedback? I'm sort of mechanically challenged

 

Topic has been beat to death on TW - some say it won't hurt a thing (I shift mine all the time), others say it's destructive and your transmission will fall out tomorrow - lol
Do a search and decide for yourself .

 

Thanks for the input, I'll get looking!