In the mid-90s i saw Willie and his band live at a small venue called Floores Country Store in Helotes, TX. They were contracted to play 3 hours: Three 45 minute sets with three 15 minute breaks.
Guess Willie was about 65 at this came out few minutes early and sang couple songs solo to a packed house of several hundred. Then the rest of the band came out and they did their first 45 minute set.
When the band took their first break Willie stayed onstage and sang more solos, just him and his guitar. in fact, he was on-stage for over 3 hours, never taking a break.
I'm seeing he's 80 now and still touring. trying to find out what kind of vitamins this man is takes!