Whether this is your first time engaging with Mindfulness Meditation or are experienced in this practice, this breathing meditation is always valuable.
The key is to just try. The first time you may (will most likely) find your mind wandering away from your breath. The act of bringing your attention back to the breath is just as important in developing your focus.
The lesson here is to engage in the mindfulness meditation without judgement. There is always room for improvement as you practice.