I have begun reading Thomas Merton’s The Waters of Siloe, which follows up his wonderful autobiography, Seven Storey Mountain. This book will give more detail to his life at the monastery in Kentucky.
Early in the book he gives a reminder to monastic orders, or spiritual orders of any kind, really, that is a great reminder for me in ministry.
…it is always a dangerous and insidious temptation for religions to abandon some important element of their Rule in favor of something else that seems, from a human point of view, to be much more useful and valuable at the time. The greatest enemy of religious Orders is not the persecutor who closes monasteries and dispels communities and imprisons monks and nuns: it is the noonday demon who persuades them to go in for enterprises that have nothing whatever to do with the ideals of their founders.
While Merton refers to the Orders, I find this an incredible word of encouragement and warning to the Church in general. I find it a shout from the Spirit to my own life. Maybe if I put it in some “country western” vernacular: “Dance with the one that brung ya!”
We keep searching for (as Donald Miller would put it) God knows what. We get dissatisfied with… with… something. And all it might be is the noonday demon trying to get us to look at the “greener” grass on the other side of the fence. Acedia (the noonday demon) is something like lethargy. We just get tired of whatever it is we’re doing and we think changing things up might help.
The spiritual fathers of the 4th century had a great spiritual weapon to battle this noonday demon: Stay at the task. If the temptation is to leave the noonday prayers (in a monastic order, for instance), stay at prayer. If the study of the Word isn’t “doing it” for you, stay in the Word.
The spiritual weapon for lethargy is persistence. It is to learn to battle through. It is to TRULY learn to hear the voice of God and understand that sometimes what may “bore” isn’t the thing itself. It may be the noonday demon trying to throw us off course. It is important to learn to HEAR the voice of God, then make our move.
Apprentice 2 Jesus 
“Stay at the task.” I should pin this to my head!
Writers have a similar phrase, an acronym really, “BOC.” It means “Bottom On the Chair.” No getting up to clean the kitchen or the floor under the computer or the laundry that hasn’t been done. Just sit in the chair and write.
How much more do we need this reminder of persistence in prayer!