To gauge fitness levels accurately, individuals can perform a series of fitness tests that assess strength, endurance, flexibility, and body composition. Common methods include the cardiorespiratory fitness test, which measures the efficiency of the heart and lungs during exercise, alongside strength tests like push-ups or squats. It's essential to perform these tests under consistent conditions and, if possible, with professional assistance to ensure accuracy. Self-assessment tools, while useful, are often less precise than formal evaluations conducted in a controlled environment, such as a gym or fitness facility.