Eric & Jessie James Decker Reflect On 'Grueling' 'Special Forces' Experience

Eric and Jessie James Decker are starring in the upcoming season of "Special Forces: World's Toughest Test" ... and when they reflected on their experience on the show with TMZ Sports this week, they ensured it was "grueling."

The couple talked all about their time on the hit Fox program while out at LAX ... and they said while it was certainly challenging, they both had an awesome time.

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"I enjoyed seeing her in that kind of element," Eric said. "We obviously had each other for support, but to see her kind of in a rugged, tough environment showed me a lot of character."

Jessie -- whose dad served in the military -- said she's always had…