Weekend hiking trip almost ended in disaster

Took my 8yo and 11yo up to the Appalachian Trail last Saturday for what I thought would be a nice 4-mile loop. Seemed easy enough, right? WRONG. My 8yo got tired after 2 miles, started complaining her legs hurt, then just... stopped moving. I had to basically carry her the last 1.5 miles. My legs were burning, my patience was thin, and my wife kept giving me "I told you so" looks. We made it but it was rough. Pretty sure my hiking days are on hold until they're like 14.