Dan was inspired from an early age. His mom painted pastoral murals on his bedroom walls and Disney scenes on his window shades. He grew up exploring the woods at the edge of his yard, and the impressions of those moments of sunlight illuminating the trees and rippling on water can still be felt in his work.

Dan went to college to study glassblowing, and that, too, had a profound effect on his painting. Hot glass has a light of its own. It glows from within, and passes through dramatic changes of transparent color as it cools. He views the world through that lens of transparent colors and sparkling chips of colored glass, and tries to reflect that in his work as he elegantly tells the story of quiet, timeless places.

Trips to Glacier and Western Montana, as well as the Tetons, Yellowstone, and the Colorado Rockies made a transcendent change in his life and work. The experience helped define his work in general. He realized he wanted to capture those undisturbed wild places, to stop a moment in time, hold a note, a breath, a transcendence above the ordinary, held in the light through the leaves or its dance on the water, to welcome the hikers, explorers and the curious who can’t help but wander off the beaten path. The work captures the color of crisp morning light filled with promise, or the softening light of evening’s approach, or the last light of the gloaming where colors of the day shift almost imperceptibly.

Janealla Killibrew, board chair of the Findlay Art League describes Knepper's work as, “.. large landscapes of the American West, reminiscent of German American painter Albert Bierstadt... Dan's realistic depictions, selected and perfected from images observed while visiting mountains, lakes, woodlands and creatures that inhabit them, are carefully modeled and intricate."

Dan's work has been in International Artist magazine, Fine Art Connoisseur, American Art Collector, Western Art Collector, Western Art and Architecture, Watercolor Magazine, The Artist's Magazine, Southwest Art Magazine, Plein Air Magazine, Airstream Life Magazine, on the cover of Of Rust and Glass Magazine, etc. He is represented by galleries coast to coast and his work hangs in collections across the country.