One thing I've noticed is that I think I'm gassed but then a fish shows itself and I can pull it together pretty well for the shot. When I start missing the shots by a mile, then I know I'm truly done.
These type of outings are combination structure and sight fishing with 5-9 weights, standing in my kayak. Used Weighted flies, floating line, and fished in depths of zero to 3 or 4 feet.
Sometimes fly fishing is as relaxing as anything I can think of. Other times, it's like an athletic endurance training.
Someone suggest I had signs of heat exhaustion and dehydration. Maybe so, but I feel better after these hot trips , sleep better, and feel better the next day.