This was long before strength training was en vogue in Hollywood or elsewhere although he did it more for his roles since he also did all his own stunts. Conrad even graced the cover of the October, 1962 issue of Strength and Health Magazine.
Greenwood Lake is a nine-mile finger of water that extends right into New Jersey and offers spartan living and a way to get away from civilization. There were plenty of roads, footpaths and other natural amenities that boxers could take advantage of for their preparation efforts (as you can see above.)
… and, in addition, thanks to the wonder of modern technology, we can show you the Marciano v. Matthews fight as well: