If not too far, Columns Dr, used to be a Mecca for triathletes to bike/run. Many in your general age group. Been a while since I trained there, but great place, if traffic still reasonable, to time trial (5 mile loop) and follow with 5k run on dirt/gravel or back out on road.

In addition, Sports Factory https://sportfactoryproshop.com/, May point you in right direction.