Combine lemon zest, lemon juice, oil, thyme, and garlic in a large bowl. Season chicken tenders with salt and black pepper; add to lemon mixture and toss to coat. Set aside to marinate, about 5 minutes.

Coat a nonstick skillet with cooking spray; place over medium-high heat. Remove chicken tenders from marinade; shake off excess. Add chicken tenders to the skillet; cook until lightly browned and cooked through, about 4 minutes per side. An instant-read thermometer inserted into centers should read at least 165 degrees F (74 degrees C).