How to build muscle mass without going to the gym

I am a fitness enthusiast who enjoys exercising regularly. I have an open mind to learning new workouts, as this will make our workout more exciting such that we don't have to do the same exercises all the time. More importantly, this will give us that muscle shock which ultimately leads to increased muscle growth, as our body is not used to a new style of exercise so it reacts differently. I am extremely passionate about helping others achieve their fitness goals, and my way of giving back is through sharing new exercises that I learnt with others.