The three tenants of DevOps are people, processes, and tools. As technologists, it is extremely easy for us to focus on tools and processes when implementing DevOps and assume that those translate to a good culture through making people's jobs easier, and thus making the people happier. This is an unfortunate fallacy. Culture is so much more than just having happy employees. In fact, I would go so far as to state that culture isn't even about having happy employees. Are you able to define what culture is about?
Get your culture right and the rest can very easily fall in to place. But get the culture wrong, and you'll be kicking and screaming while you try to rectify it down the road.
I have personally worked with Dr. Laura Gallaher and her team in a setting where culture meant the difference between success and failure. They are well worth every penny you might spend. Check them out here: https://gallaheredge.com/