Alva was born on a homestead near Chugwater to Bert and Agnes Miller. Early in his life, the family moved to the Whitcomb Ranch on Chugwater Creek, about six miles west of Chugwater, where Bert was the foreman for the Swan Land and Cattle Company ranches west of Chugwater. At that time, the Swan had numerous sheep herders dispersed across their vast acreage. When Alva was 9 or 10 years old, he and his older sister, Georgia, were hired by the Swan for a few summers to individually take a team of horses to the different sheep camps and move the sheep wagons to new grazing areas. Bert had struck a deal with the Swan that he would work as the foreman in his designated area but he could also run his own livestock on their land, maybe 50 head or so. The type of livestock was evidently not specified in the deal, and Bert chose horses. It became Alva’s job to break the horses so that they could be sold as “remount horses” to the US Army. Alva then moved on to the now famous Diamond Ranch, southwest of Chugwater, in Albany County, to tend to cows and break horses for the owner, Mrs. Overmier. She had a passion for polo and was impressed with Alva’s skill at breaking “cow ponies.” She started having him train her most athletic ranch horses for polo. After his marriage to Faye Rhoades, Alva returned to Chugwater where he was employed by the Swan Company as a ranch hand. He also worked for other ranches in Platte, Albany, and Laramie counties. In addition to breaking horses and doing other cowboy work, Alva broke several light-driving teams and he trained a lot of chariot racing horses.