First things first, you don’t have to have a mindfulness teacher because all you need to know is
Breathe in and know you are breathing in; breathe out and know you are breathing out.
That is it. So yes, you could say anyone who is a mindfulness teacher is a fraud because as far as I can see all the guidance you need is in that phrase. Yet nearly every mindfulness teacher you meet or can listen to will openly state they are unable to follow that instruction the whole time or probably even half the time.
So attending a class or following a course will help you see that mindfulness is also ‘present moment recollection’ as Christine Feldman described it. Just this breath and this moment…. but then this breath has passed and this moment is gone and you have to start again or, if you are fortunate, carry on. Within “breathe in and know you are breathing in; breathe out and know you are breathing out.” is a lifetime’s experience and wisdom. Mindfulness whilst simple and clear is also not to be summed up in a pretty meme or statement. Those are just the start.
So being in a class or following a course allows you to practice mindfulness in many moments and the practice is made that much easier by having a teacher who can help you help yourself and being with other participants to let you know you aren’t the only one feeling these things and thinking those thoughts.
The mindfulness teacher can only be a guide, it is the mindfulness that will teach you again and again in each and every moment you are aware of.