Warm up with 5-10 minutes of light cardio and dynamic stretching to prepare your body for the workout. For the circuit, aim to complete as many rounds as possible in 20 minutes. Start with the bike erg and maintain a steady pace throughout. For the lunges and thrusters, choose a weight that challenges you but allows you to maintain good form. Break up the reps as needed to avoid burnout. If you don't have access to a bike erg, substitute with another cardio machine or a 400m run. If lunges or thrusters are too difficult, modify with bodyweight lunges or air squats. Remember to cool down with static stretching and foam rolling to aid in recovery. The goal of this workout is to improve endurance and strength in a time-efficient manner.