DO. YOUR. PULL UPS.
The pull up is the only exercise that should indefinitely remain in your training regime no matter your goals. It serves as an excellent marker for general health and fitness, and the exercise itself seeks to develop every single positive athletic attribute. This exercise is also one of the best back building exercises out there, as it's versatility and convenience allows you target each muscle in the upper back depending on which of the endless variations of this exercise you choose to perform.
Do your pull ups.