Wrestling is a very tough sport. You must be able to have explosive power for a take down. You must also be able to maintain that power for about 5 minutes. What you need to do is improve your anaerobic conditioning level.
Many wrestlers make the mistake of going for long slow three- mile runs to get in shape.
This is not specific to wrestling. In fact, training for endurance may actually decrease your power. You need to train your body to recruit fast-twitch fibers and buffer lactic acid that accumulates. The way to do this is through anaerobic conditioning. Anaerobic basically means without oxygen.