One of my first spiritual directors gave me some advice that I have always struggled with, but in a good and productive way. I asked him how much time I ought to devote to prayer in a day or a week. He said, "More than you want, but less than you think you should."
We should pray more than we want to.
If you're anything like me, you protest right away. But I want to pray all the time! I want to pray always as the Scriptures command! So how could I pray more than I want to? This apparent problem is important for our spiritual self-awareness. Do we want to pray always, or do we want to want to pray always? There's a big difference. To take a simpler example, we may say that we want to eat apples instead of candy, or drink water instead of gin, but it's really that we wish we wanted to change, not that we want to.
Any person who tries to get serious about a prayerful life knows this conflict. We want to be the sort of person who is utterly committed to prayer, but we soon find that this isn't who we really are. Sometimes we feel like praying and sometimes we don't. To keep our rule of prayer and to pray earnestly and intentionally precisely when we don't feel like it is critical to our spiritual growth. This our invitation into the "night of sense." To pray through our dryness of lack of delight in prayer purifies our motivation and offers us the great gift of not becoming attached to the consolations that are meant to help beginners get going.
We should pray less than we think we should
Every serious religious person has a kind of image of herself as the saint she wants to be. This is a good and holy desire, and helps us to strive to go beyond ourselves as we are. Sometimes, though, this gets to be an obstacle when what we really want to worship is the idea of ourselves as a holy person rather than the living God. When this gets really bad someone walks about, missal or breviary bulging with holy cards, in a self-satisfied stupor covered by a kind of affected humility that even a child can tell is fake. He is not in love with God, but with religion and the idea of himself as a servant of God. The religious self can be a powerful idol, and one the devil is happy to encourage.
If we are honest, we will hardly have to try at praying less than we think we should; anyone with even meager self-awareness will realize that he is not living up to his own expectations for devout prayer and religious practice. Instead of letting this produce a self-involved discouragement, this experience of not be able to pray as we ought should invite us to the humility that depends only on God. "The Spirit too comes to the aid of our weakness; for we do not know how to pray as we ought, but the Spirit himself intercedes with inexpressible groanings." (Romans 8:26)
This is the big "Aha! moment" with prayer, but also one of its hardest challenges: it is not something we do at all. It is not our activity or project. It is the life of the Blessed Trinity come to live within us, the prayer of the Spirit that has made a home in our spirit through our communion with the humanity of Christ. To realize this is a great liberation, for we only have to consent rather than do anything, and we have no credit in it, and thus no occasion for vanity.