We must remember that the body is very important when we are praying. There is no doubt that the prayer is a spiritual task but the corporal attitude has influence in the spirit and establishes a certain harmony and synchrony between body and spirit.
Generally speaking, it is convenient to maintain a humble and respectful posture. The ideal is to kneel down, but this rule should not be carried out rigidly or with exaggeration. In the Bible we can find examples of a number of postures: standing up (Luke 18, 11), sitting down (Luke 10, 39), kneeling down (Luke 22, 41), prostrated on the ground (Mark 14, 35), in bed (Psalms 6, 7).
Whatever posture we choose we have to avoid:
• Excessive comfort, for example trying to pray in bed until we fall asleep.
• Extreme mortification, because this kind of posture does not help to pray, on the contrary it makes the person get distracted and he/she stops wanting to pray.