A habit is automated behaviour. We do it without thinking. Habits help us save energy and reach our goals by being consistent.
Mindfulness is the ability to focus on the present and return our attention again and again to this very moment. It calms us down and improves the quality of experience because we are not distracted from life when it unfolds.
They seem like opposites but they are not. We can decide to mindfully brush our teeth, even though brushing our teeth is a habit. We can establish a habit of mindfulness meditation every day. Or we can decide to engage in mindless habits if we would rather multi-task.
However it’s important to understand that we have a choice. If we forget that we are just subject to random decisions our brain makes for us instead of the other way round.