Is it OK to do vigorous cardio AND lift? I have heard mixed signals about this. Some people have told me that they only lift and to avoid all cardio because it will fuck up your gains while others have told me that you can't have one without the other and be healthy. Someone even told me that hardcore cardio severely lowers your testosterone levels, but one guy I know basically just works out all day (he lifts and is always exercising whether it's walking or running to a store, playing sports, swimming, etc.) He has an amazing defined body that bitches go crazy over.

Getting into lifting has been easy so far for me. But I've found some cardio activities to be a bitch. If I go running I quickly run of steam. Do you just gradually build up your endurance over time? Do you need specific running shoes for performance?