Hard to know what over the hill is when you regularly see folks in their 60s and 70s doing 20 mile days most days on the AT and other long trails - and 20-somethings knocked out after 15 miles, groaning and limping around camp. Now, it is true that 20-somethings can roll up 30 to 35 mile now and then. But they tend to sleep it off the next day. Perhaps being over the hill means having the judgement to know one's mileage limits. But maybe judgement comes with the discipline to meet goals and the experience to know one's limits. But let's not assume that those limits are low.