What should we do if we have a healthy prayer life, but still feel like we're missing something?
Everyone uses something called "executive function," which Fr. Spitzer referred to as "psychic energy". It's the mental effort we exert to take in information, make decisions, and communicate with others. Like our bodies, our minds can grow tired too, especially when we use up a lot of mental energy to concentrate on a specific task - like prayer.
An article in Scientific American explains: "When you focus on a specific task for an extended period of time or choose to eat a salad instead of a piece of cake, you are flexing your executive function muscles. Both thought processes require conscious effort-you have to resist the temptation to let your mind wander or to indulge in the sweet dessert. It turns out, however, that use of executive function—a talent we all rely on throughout the day—draws upon a single resource of limited capacity in the brain. When this resource is exhausted by one activity, our mental capacity may be severely hindered in another, seemingly unrelated activity."
When we commit too much executive function to certain tasks, we can encounter "decision fatigue". According to this article from the NY Times, "Decision fatigue helps explain why ordinarily sensible people get angry at colleagues and families, splurge on clothes, buy junk food at the supermarket and can’t resist the dealer’s offer to rustproof their new car. No matter how rational and high-minded you try to be, you can’t make decision after decision without paying a biological price. It’s different from ordinary physical fatigue — you’re not consciously aware of being tired — but you’re low on mental energy." This can help explain why someone who spends a lot of time everyday in prayer may grow impatient and angry by the end of the day. We need to make sure that we save some of our mental energy for those we go home to.
We hear about saints who prayed for hours on end in the chapel, and of course we want to emulate them, but should we? Put it this way, if you wanted to run a marathon right now, could you do it? Assuming you're not currently training for a marathon, probably not. We can condition ourselves to be in the right physical shape to do so, but we need to have the time and opportunity to do so. It's the same way with mental energy.
When we have the time and ability to do so, we can and should devote ourselves to time with God, studies even show that it's good for us, but we also have other responsibilities that God Himself has given us. A student must study, an employee must work, and a father must care for his child. God wants us to pray as much as we can, but it should be in its proper place within the greater vocation of our lives.
You can also cut down on decision fatigue in other ways. Check out this article from Forbes for tips on how to reserve mental energy.