Might I be getting old?

After getting up at 4 to fly to London, walking for 20 km and getting soaked during the last 5 km thanks to heavy rainfall, standing in line for 3 hours in shorts/t-shirt in 4°C momentary rain, and jumping at a concert for another 3, I feel really spent.

But the real kicker is that after the concert, another attendee I talked with in line, says he felt really old attending a concert with so many younger people. He was 10 years my junior. And yet another attendee turns out to be one third my age.