Knowing your body type is important before starting.
There might be some people out there who think that every one is born with the same body type....this would be easy if that was true.
When first beginning your fitness journey you will want to know your body type and this is a good reference to go by:
If you are skinny and you have a very fast metabolism than you would classify yourself as a Ectomorph.
If you are naturally athletic and it is very easy for you to control your results (lucky you) than you would be classified as a Mesomorph.
If you have a slow metabolism and gains fat very easy than you would classify yourself as a Endomorph.
