When you work out, stress on the muscle activates chemical pathways that increase the rate of synthesis, so now the net effect is to build muscle tissue. The muscle damage ('tearing') you mention is one signal for synthesis, but there are many more (metabolic, hormonal, dietary, etc)....
Although tuition varies greatly by year and has significantly increased over the last decade, medical school averages $34,592 per year and $138,368 per degree for in-state students at public schools and upwards of $50,000 per year or well over $200,000 for private institutions as of 2017.
He is looking at about 10 years of hard work including taking a year of post-graduate pre-med science courses, four years of medical school and five years of surgical residency training before his dream becomes reality. Here are the issues. He is still paying off his college tuition loans. He will have to pay tuition for his post-grad year. Medical school tuition alone will cost at least $40,000 per year [private] or $20,000/$40,000 per year [public, resident/non-resident].