In fact, just by walking (ok more like racewalking), the first time i ran 1.6k (2 rounds at my place) i stopwatched it at ~ 6 mins 20 seconds. Which is a wee bit below 4.00 pace. Q4 of 2022, or around 2 years 3 months of racewalking (i think i just brisk walked for a few months before adopting racewalking).
No other runs or jogs. Why i decided to run is coz i just got my Adidas Takumi Sen 8 and wanted to get into running, so i just timed it.
Ok so granted, i did SITs as well so that's sprinting, but not as if you'd need some specific running plans with structured training.
Why i racewalked, is also coz of similar to llchl thinking / reason, coz i wanted to protect my knees, coz i am also in my 50s, just like some of you here with the exact same thinking.
Later just ventured and "risked" into runs. And of coz now still sticking to 1.6k-10k "TT"s, long runs of 12k i do a bit here and there ba, lately i tried up to 16-18k but feeling a bit tired.