I use to wrestle basically its just perfecting your craft, you just need to constantly be wrestling during the off season i wrestled 2 times a week for 2 1/2 hours each time and during the summer I wrestled 6 hours a day for 2 weeks straight then right before the season you gotta tune it up and go 3-4 times a week. It takes a lot of dedication but in the end its worth it. What I've learned you don't need to be the strongest or have the most endurance its all about technique.
PS work out in the gym being stronger helps a shit ton.