He had a gig mowing lawns at 11. By 25, he had turned it into a multimillion-dollar landscaping business.

Cody Kuebler, 25, started mowing his neighbors' lawns when he was 11. CLK Landscape Construction He began by cutting neighbors' grass for about $25 a lawn. A move at 14 meant rebuilding his customer base from scratch. He now oversees millions of dollars' worth of equipment — and works six days a…