I'm 47 and I never ran for exercise in my life. I live next to an outdoor running track, so like everybody else during the pandemic I decided to start running: the very first day I ran just 1 lap (450 meters, as an amateur I know we have to be at the outer lanes). The second day I was able to run 2 laps, but given my age I thought that I should increase just 1 lap per day, to avoid any cardiac surprise. Thus I ran 3 laps the following day, then 4, and so on. A few days later I was very excited after running 5km (12 laps, pace of 6:33min/km). I thought I was being prudent by increasing just 1 lap per day, looking after my heart... little did I know that I completely blew the 10-percent rule ("never increase your weekly mileage by more than 10 percent over the previous week").
I had a knee injury so bad that I was almost unable to walk for a couple of days. After 40 days my knees are 100% fine now, and during that recovery I read a lot about running (the 10-percent rule, stretching, running form etc...). Now I want to start running again, and I do understand the importance of the 10-percent rule.
But, as a beginner, my question is "10 percent of what"? What should be my initial milleage? Obviously "just run until you feel you need a walking break" won't work because now I know that I'm able to run a dozen laps without walking breaks (but destroying my knees in the process).