He needs to go through a lot of aerobic work which is long distance running and then into anerobic which is short and fast work.
He needs to run for an hour, 4 times a week for a month then add on anerobic work
Run fast 60m up hill then 40m then 10m recover for 30 seconds then start again do this for half an hour. Do anerobic work 3 times a week. Then once a week do a lactate sessions once a week which is going to fatigue.
Run 400m then 200m and then 60m, rest for 5 minutes then do it again 3 times
Then do 10 squats on rugby field run out 25m sprint back then run out 50m then sprint back then run out 60 m and then sprint back recovery time 30 secs then do again 3 times