Important if not more important that the miles and training. I use recovery in a structured fashion just as I do training. Very important to my training is rest. Hard. Sessions and tough training weeks equal a focus on rest and downtime. My coach has me in mini training periods after a big race. I come back to training after 5 to 10 days off feeling ready and refreshed.
Post workout: I incorporate rolling using a trigger point roll 3 to 4 times per week. This I will do to "iron out" muscles in my upper abs lower legs. Vital.
Another integral if not the most important part for muscle recovery is protein. This article in Runner's World illustrates how protein post workout is vital to maintain and promote muscle repair. https://www.runners world.com/advanced/a20826161/post-run-recovery-starts-with-protein/
I drink a half of a protein shake made with CocoaElite Protein powder, ice cubes and a half of a banana. Daily. 30 minutes after my session. This helps my muscles recover. This study below shows how important Whey Protein is in the recovery process after high mileage and marathons. I average between 80 and 100 miles and I believe Whey Protein to be vitally important to ingest within 30 minutes of a hard session. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562115/I try to make my protein shake the night before then I can sip on it for hours after my workout abd at work. I use the CocoaElite protein powder in ice cream as well! Yum! My new favorite protein to use is the CocoaElite overnight protein powder. Twice a week I will mix this into ice cream and eat it before sleep- twice the recovery! This article below highlights the importance of sleep and the athlete. Sleep is so needed almost as much as the training itself . https://journals.lww.com/acsm-csmr/fulltext/2017/11000/Sleep_and_Athletic_Performance.11.aspx
Another article from The Washington Post shows sleep as a " magic pill". All the more reason to turn off my phone and rest. I have found my sweet spot is 6.5 hours although I can get- by on 6! Add in the Whey Protein before bed and my muscles will get a double dose of recovery time.
https://www.washingtonpost.com/national/health-science/why-a-good-nights-sleep-is-the-magic-pill-for-athletic-performance/2019/02/08/c58351aa-2492-11e9-ad53-824486280311_story.html?noredirect=on&utm_term=.6b659d2b73ef