Although it would seem like you’d need weights in order to build your muscles to their maximum capacity, that isn’t true at all. In fact, you can get in a great full-body workout using nothing more than your own body weight to provide all the resistance you need. Therefore, if you want to build muscle mass but don’t have or want to use weights, here are the best exercises to do:Push-ups. Getting in the prone position and pushing your body up and off the floor is a great way to work your arms, back, and core. To make these exercises harder, pull your hands in closer together so they are right below your chest. You can also do one-arm or one-leg pushups to test your strength even more.Pull ups. Go to a park or find another place where you can grab ahold of a higher spot and pull your body weight up and off the ground. This will tax your arms and upper back, giving you a great upper body workout without any equipment at all.Lunges. It may not seem like these elongated steps would do much for you, but do a few of them and you will soon realize how much they work your thighs and hamstrings. To push your legs even more, try side or back lunges as each one hits your muscles in a different way.Squats. Squats are another lower body exercise that will leave your thighs begging for mercy. Not only do traditional squats do the trick, but so do wall squats, where you lean back against the wall in the squat position for as long as you can handle (which usually isn’t long after your legs start to shake).Do these four exercises and you can grow your muscles without buying any bulky or expensive weights.What are your favorite weight-free strength training exercises? Feel free to share them below!