While building your physique is ultimately all up to you, having someone there to train with you can be that very boost you need to better yourself.
Watching "Generation Iron" made me realise how important it is to have like-minded people around you to work and play together, pushing each other to improve themselves.
The many fitness instagram accounts I follow also reinforces this fact that no man is an island and having a gym/training buddy can really help you stay the course.
Need a gym buddy!