For good or for bad, culture is nothing more than the behavior of its leaders.
Start by examining your character. Are you thinking, feeling, and acting in morally relevant ways? Does your character model your core values? People will always do what you do, and not what you say. Spend some time examining your integrity. Do your actions match your words? Finally, envision a company where employees are honest, trustworthy, and loyal. Model behavior that will create trust and build a healthy environment where people genuinely enjoy coming to work.
Lead with intent. Set the example for character and culture in your organization.