If you've ever felt your form slip during a tough workout, you may have put yourself at risk for injury. Try interval weight training designed by CrossFit athlete Marcus Filly to boost cardio and strength without sacrificing quality. In under an hour, warm up with purpose, train with high threshold aerobics, and finish with knee-strengthening exercises. All workouts can be scaled to your fitness level. Add weight to your warm-up and focus on anterior and posterior chain exercises. Working on cardio and strength is crucial for overall health and well-being.