Good for you! I used to run quite a bit about 15 years ago, but I lost alllllll that conditioning.
Now I run maybe 5 miles a week.

I started with track doing the 400m, 800m, mile, and 2 mile events. That expanded to cross country events (even one steeple chase........holy that was tough).

That expanded into a few half marathons, and three tiny iron man competitions. NOT the full sized ones. I never quite got to that level, and those people are badasses.

Are you focusing on anything in particular? Long term goals? Distance, sprint, trails, etc?