The spiritual man knows that he must watch out for himself because the remains of his sinful nature will rise up at even the most holy of times.
Satan works in the presence of God (Job 1:6-12) so why would we think that we can avoid his influence when in prayer?
It is during this time when we might be the most likely to let our guard down and forget to observe ourselves for signs of self-worship. "Not me!" you might cry, but do you not find that your prayers become a matter of boasting, or a message to others who are praying with you, or a point of satisfaction when you have finished that you have prayed for the day and can now feel good about yourself?
The prayer of the spiritual man seeks much help from God because he knows that he is prone to doing it wrong, with his mind on himself much easier than his mind on God. Every moment of mental space throughout the day can be used to consider the majesty of God, and then when prayer is begun, this sense of His glory will help to forget yourself.
God help us to be better children in communion with You!