[PaulDavisThe1st]

I don't think you're familiar with the performance levels of masters (40+) atheletes.

I'm 60 now, but in my 40s I was a moderately good marathon-to-ultramarathon runner, and with a little bit of speedwork training, I managed to run a 5:30 track mile. That's not even fast - I had friends of the same age who could run 4:30.

It is truly remarkable what the human body can do - the world record for the marathon involves running 26.2 miles faster per mile than I could ever run 1 mile.

But if you can't sprint faster than 4mph for a few seconds, that's fine but it's not indicative of "at your age". Unless you have some actual health issue that prevents it, I would very surprised if you were incapable of hitting 6mph for a mile with some training, and a lot of people would not find it tremendously hard to hit 6.5-7mph if they had the time and motivation to train.