In order to build muscle you need to consider the following -
1. Overload principle – In order to get your body to adapt, then you need to train to the point that you have overloaded your muscles.
2. Over training – Rest can be as important as training at the correct intensity, without enough rest your body will be unable to adapt and grow as you require.
3. Sleep – With out the required amount of quality sleep, your body will be unable to recover fully and this will inhibit muscle growth.
4. Cardiovascular Training – Too much cardiovascular training can result in the body adapting to have smaller more efficient muscles.
5. Food – Getting a balance of enough food, with the right quality and the right proportions of protein, carbohydrates and fat is vital to getting a muscle to grow.