The park near my first apartment didn't have a proper track, just a loop of cracked sidewalk with a hard dip on one side. I found the dip by rolling my ankle five minutes into the first run I'd attempted in years. I kept training on that same stretch anyway, mostly because nobody told me a beginner was supposed to go looking for something better.
Your first day
Starting takes twenty minutes. Put on shoes that still have spring in the sole, press a thumb into the bottom and check it rebounds, then set a phone timer for the intervals and walk out the door to a flat, even path.
Walk for two minutes to warm up. Then jog for one minute and walk for two, six times through, and repeat this every other day. The jog pace should feel almost too slow to count as running, slow enough to hold a conversation through the whole minute.
Most people speed up during the jog minutes because the slow pace feels pointless. Don't. Running faster than that in week one is a common route to the shin pain that ends many people's second week. If a pain is sharp or on one side only, stop and rest.
The thing most people miss
My first month of running was mostly gritting my teeth through jog intervals that should have felt easy. Then I checked my watch on a run I expected to feel like ten minutes of jogging and found it was closer to nineteen. The gap between how long it felt and how long it actually was told me more than any coaching advice had. I'd been running close to a minute per mile faster than I needed to, the whole time, without meaning to.
Once I slowed down on purpose, I could hold a full conversation through jog intervals I used to dread. The discomfort I'd been treating as the point of running turned out to be a pacing mistake, not a personality trait I lacked.
What not to do
Don't run two days in a row for at least the first month. The legs and shins need the days off between sessions more than the running itself does the work. Most early injuries come from skipping the rest day, not from the running being too hard.
Effort that still allows a normal conversation is the actual pace, not a beginner's placeholder for real training. The single most useful addition from here is a second kind of run: one slower than every other run on the calendar, extended a little further each week. That's the piece everything faster eventually stands on.