Your 20k pace is my 10k pace, HS.
Didn't get up to the 15 miles p/week by July like I hoped at the top of this page. Ran 12 in the last 7 days, so getting there. I'm out of shape so I had to take more rests and run a bit shorter than I thought I could. HITT/intervals are getting me there faster, but I honestly I hate doing them. I'm at 8,300 feet and running hill sprints is punishing.
I want to get out on the trails but they've ridiculously crowded, parking is a nightmare, etc. Just gotta bite the bullet at some point, because there are some great runs out here.