I am a high school freshman who ran cross country this year. I PR'd about halfway through the season with a 21:46, but was set back with a minor season-ending injury. How can I gradually build my mileage for the next (about) 7 months, from the beginning of November to the end of May so that I get better without getting injured? I want to start at about 15 miles per week, maybe even 10, and build up to about 50-60 miles per week. My longest run in about a month is about four miles. Next year, I would like to run a sub 19 minute 5k, so I am training in the offseason to get better. I am also NOT doing track (please don't try to convince me to do so, I just want an answer to my question)! Thanks in advance!