I seem to be older than those who have admitted their age on this thread - I'll be 70 before the end of the year. But I didn't really have any problems with exhaustion at all. Yes, I'm a bit tired today but nothing out of the normal.
BUT, this being my 13th festival since 2005 (but I did go to the Bath Festival of Blues & Progressive Music in 1970 which started it all), I have always volunteered with WaterAid. The experience in the first years wasn't much different to the regular punters, camping in crowded conditions in the centre of the site with no "perks".
For the last few years we have camped in Brimley's Orchard next to the recyclers in Tom's Field. We now have our own compost toilets in the field and even better toilets a short walk away, plenty of decent showers and a canteen with some free meal tickets and subsidised food and a crew bar with probably the best ale on the site, combined with it being the cheapest - £3.50 a pint. Talking to a couple in Worthy View it seems to be similar in facilities but with smaller queues and only a modest slope to climb up every night.
We obviously have to work, 4 x 6 hour shifts over 5 days with a day off. But even with the short straw rota with a day off on Thursday and 6pm to midnight shifts on both Friday and Sunday we still had a great time. Working is almost as much a highlight as the rest of the delights - meeting a huge cross section of festival goers. I saw a grand total of 9 acts over 4 days and only 5 on the "main" stages and some of them only a part set. But we had all sorts of other interactions, met and drank with a lot of friends.
Maybe if I get another 2007 I might be tempted to call it a day but as long as my health holds up I'll be back. But volunteering - hugely enjoyable, a free ticket, no angst getting a ticket and a Tuesday arrival so no traffic or queues. Tuesday is one of my favourite days, seeing all the green fields but plenty of bars open and lots of friends there.