Simply said, your fitness plan should include both aerobic and strength exercises. Strength training can be done with your body weight or using weights. As you gain strength and need a challenge, you can increase the weights you use in your routine. Cardiology is still important, though, and shouldn’t be disregarded. Try doing high-intensity interval training (HIIT) many times a week to get the optimum muscle-building effects. What is the recommended frequency of exercise? Research suggests doing strength training twice a week or more to increase muscle. As a result, start with two or three days of cardio, followed by two days of full-body weight training and two days off.