Taking a breather. Both of us are used to daily flat-level walking, so doing moderate "mountainous" hikes AND being at a lot higher elevation than we're used to where we live in Central Texas, contributed to us being a lot more out-of-breath than usual when we'd take a hike to see a waterfall (for my pleasure). We're also used to only doing 25-45 minutes of exercise at a time back home, but some of our hikes in the GSMNP took us 2.5 - 3.0 hours to complete.