Dr. Robert Coleman, my faculty advisor while I was in seminary, used to say that "a rut is just a grave with the ends kicked out!"  Yes, a rut is the closest thing to living death on this side of the grave.
No one likes to be in a rut, but we all tend to fall into one occasionally.
On the other hand, what I am really impressed with is the person who can work in the same job for 15 years or more.  I often ask these people how in the world they can work the same job for so long without falling into a rut?  And the answer is always something about either the job responsibilities changing through the years, or their own capacity to manage the job improving and growing as the years go on.
Here's the sort of things they tell me: "You have to learn to change with the roles you are assigned." "You have to roll with the roles, and manage the surprises, and live with the routines."

For those of us in full-time pastoral ministry the choices seem to be three (as they often are in our sermons!)
1.  We can Fall into a Rut.
2.  We can Work into a Routine.
3.  We can Warm up to a Rhythm.

The key is to develop a Rhythm, without falling into a Rut.

All three of these have the same elements: Actions, Motivations and Results.

1.  Falling into a Rut
Bill Hybels has frequently said that at one point in his ministry career, he realized that the way he was going about doing the work of God was destroying the work of God in him. This highlights the need for all of us in ministry to find a way to live long-term in the grace and goodness of God, even as we serve long-term in a church congregation.
Based on our elements of Actions, Motivations and Results, here's how it plays out in terms of a rut: When you are in a Rut, you are performing the same actions with declining motivation and decreasing results. That is, you are going deeper and deeper down, and it is becoming increasingly more difficult to change.

The essential problem here is energy loss.  When you are in a Rut, you are not deploying the same level of energy into your actions; this is because the source of energy and success is from your motivations which are on the decline.  Thus, the poor results.

There are two key ways we experience energy loss.  The first is through Dissipation of energy, due to inaction.  We enter into a downward spiral and then we lack the motivational energy to do more, so we reduce our efforts, and the lesser results cause a further erosion of motivation.  This is a common problem in smaller churches, and pastorates.
The second way we experience energy loss is through Dispersion of energy, due to undirected action.  While the first problem comes from not enough action, this second problem occurs when we have plenty of action, but it is undirected, and goal-less.  Dispersion of energy is a very common problem in large, "successful" American churches, where the quantity of available programs is over-whelming.  It looks like there is no lacking in energy and action, but because it is not coordinated or directed to a common goal, it's overall results are negligible.
The fact is that both large and small churches have the capacity to fall into a Rut.

2. Work into a Routine
As those in the workforce have told me, the only way to succeed long-term in a job is to get into a consistent lifestyle routine.  You have to find some way to manage the stresses of the job, and keep a semi-stable lifestyle; one which can last for 15-20 years on one job, if you want to stay there that long.  This applies to the church as well.
As for our three elements (Actions, Motivations and Results), when you work into a Routine, you are performing the same or similar actions consistently, faithfully, and achieving similar results. The more than half of American churches which are plateaued have at least stopped the downward trend and found a way to "keep on, keeping on."
The only thing that can be said in its favor is that it is predictable, and relatively stable and secure.  And that may be enough for some pastors, but not for you.  It is not too far removed from Coleman's quote about a grave with the ends kicked out.

There is a third choice and goal for any pastor who seeks to develop a vigorous church...
3. Warm up to a Rhythm
I use this language because it is reminiscent of an athlete who is warming up to his peak performance as his body gets loosened up in practice. It reminds me of an orchestra which is warming up its instruments, reeds, bows, etc. before a performance. There is an initial period of below or mediocre performance, but then suddenly, it just takes off. That is warming up to a rhythm. This is what we need in ministry.

Rhythm is the key to long-distance running;
Rhythm is the key to making music;
Rhythm is the key to a healthy marriage;
Rhythm is the key to a healthy church;
Rhythm is the key to long-term ministry.

Back to the three elements: Actions, Motivations, Results. If you are into a rhythm, you are performing the same actions, but you are taking time to "sharpen the saw" as Stephen Covey says. Ecclesiastes puts it this way: Since a dull ax requires great strength, sharpen the blade. That's the value of wisdom; it helps you succeed (10:10).

When a person is into a rhythm, they have found a way to keep growing and developing as a person, while they perform the actions required of their ministry. This increase in both knowledge and performance has a positive impact on Motivations, and of course, the Results.

Rhythm - same actions, but skill sharpening as you go, so they become better actions, thus driving motivation and increasing hope and getting better results.  It all begins with "sharpening the blade" through wisdom.
This is more than just knowledge acquisition; it is application of that knowledge in your ministry setting, followed by appropriate reflection and feedback to assess your results and improve.
The blade is sharpened, and rhythm is maintained by an on-going cycle of knowledge acquisition, applied wisdom, feedback and reflection.
I've discovered the best way to do this is through formalized coaching relationships. I've been to all of the conferences, ministerials, and prayer partners, and while they are all good, they most often fail to provide the critical elements of feedback, reflection, and refocused actions. Coaching relationships have given me this, and it has helped and improved me as a pastor. I would recommend it to you.

The Biblical picture I love to think of in this regard of falling into a rut, working up a routine, or warming up to a rhythm for life, is that of Caleb who still had all the energy at 85 to go up and attack, and claim his share of the promised land!
Here is the text for your reflection:
"Today I am eighty-five years old. 11 I am as strong now as I was when Moses sent me on that journey, and I can still travel and fight as well as I could then. 12 So I'm asking you to give me the hill country that the LORD promised me. You will remember that as scouts we found the Anakites living there in great, walled cities. But if the LORD is with me, I will drive them out of the land, just as the LORD said" --Caleb (Joshua 14:10-12).

Dr. Bill Miller