For Sara Story, every morning at her home in Texas Hill Country begins the same. “Rain or shine I go for a hike,” says the fitness-obsessed AD100 designer, who forgoes her regular Manhattan gym regimen in favor of outdoor exercise whenever she’s at the ranch. The terrain is familiar: It’s the same sweeping view that she fell in love with during summers at her father’s neighboring property, long before she commissioned Lake|Flato Architects to build a place of her own (AD, April 2014). These days, however, the crescendo feels different. Inspired by contemporary Scandinavian saunas, she collaborated with the architecture firm Clayton Korte to create a spellbinding spa, with a wood-lined structure and an outdoor cold-plunge pool, both sculpturally clad in board-formed concrete. After an hour-long trek around the grounds, she now sweats it out for 30 minutes at 180 degrees, before tiptoeing across the stone pavers to take a bracing dip in the cylindrical oasis. For the faint of heart it’s not. But this is Sara Story. “My heritage is Viking,” she notes. “The whole sauna mentality is in my blood.”