Here's my quandary.
Having got a few 10ks under my belt, I'm currently pushing towards 10 miles.
However, for my pre-run warm-up (for either solo sessions or my weekly Parkrun), I've stuck to the lovely Laura's "brisk 5-minute walk" (followed by dynamic knee-pulls, kicks and ankle-pulls.)
It's clear to me that I'm not really prepared, as I never feel properly into my stride until I reach the second km.
On the other hand, I'm reluctant to do more, even an easy jog, because I'm instinctively resistant to anything that will deplete my energy reserves.
I should say that I'm influenced by the fact that I'm very much a one-pacer - if I make myself slow down, I'm back to 180-185 paces per minute, approx 5:30-5:45 minutes km, within 30 seconds. (At 69, I don't expect to get much faster.)