A little Cardio goes a long way.

One common mistake I often see in lifters training for massive size or strength gains is that they forego any and all forms of cardio. While too much cardio can certainly impair gains, you need to have a minimum fitness base to optimally recover – both between sets and between workouts. Interval training and loaded cardio (such as sleds or carries) are both great methods for improving your overall fitness without sacrificing gains in size or strength.