Even when I do yard work...got 4-5 hours worth tomorrow....I HAVE to stop and take breaks more. Example..Tomorrow is a few hours because I'm blowing off the roof, trimming hedges, edging / weed eating and mowing. 20 years ago, I could EASILY do tomorrow's work in 2-2 and a half hours. Doesn't help that we are now in 90 degree AND humid weather.