If you have a look on google you will find so, so much information about how to sit during formal practise. There are many schools of meditation and many of mindfulness, and each of them tell their own story about how to sit in the best possible way.
How you sit is your choice.
Anyway, whatever you decide, your sitting position creates support for your integral body-mind-soul system during your formal mindfulness practise period – which can also be of variable length. If you are in the beginning stages of your practise you are likely to sit maybe 5 minutes, maybe 30 minutes. But later on in your practise you will be sitting for longer time. Myself I sit for 30 minutes in my daily practise but during retreats I sit for one hour several times a day. The sitting position is your support. Please be careful and thorough when choosing and practising.
Text and photo Anne Moloney, 18082018