In these practices always maintain mindfulness: Yoga is the art of combining the breath with movement to achieve a meditation state. Unpleasant and pleasant sensations may arise. Be open to receiving the communication from your body and elsewhere. 
Practice is a safe space with a ritual of a shower and some warm tea before commencing. Warm the body and allow yourself to cool down afterward.
It is not a competition with yourself but more an exploration of the magnificent way we are present on this plane and planet.