When to cut 'em loose

How do you know when to quit pursuing a professional ministry relationship that is not moving forward? What do you do when you have a volunteer or (in my case) a student in ministry who is not where they need to be? How do I know when to keep pursuing them and when to move on?

For me, it comes down to 3 things. These things are in escalating order of importance. In other words, number three is more important than number one.
1) Your bandwidth
The amount of available time and energy that you have to invest in this person definitely comes into play. If you're out of energy, this really limits the amount of time you have to invest in unmotivated people. However, if you have spare time on your hands, then go for it, even if they're tough.
2) The person's value to you personally or the organization
For the organization, value is equal to the amount of leadership potential. To quantify leadership potential, read John Maxwell. Ask yourself, "is this a person that people naturally look to for decisions." If so, more effort is warranted than if the answer is negative. I use the calibrated gut to put people into a 1-5 (5 being great potential) grid of possible influence on others.
3) The teachability of the person
This is the most important issue. I want to spend the majority of my time with people who are teachable. If a person has a leadership potential of a 5 but 0 teachability, I pass them by. However, if there is any teachable attitude present, they would be well worth the effort. I would give a 5 LP 1 Teachable much more effort than a 3 with the same teachability. However, I would invest in a 3LP who was teachable over a 5LP any day!

No matter who they are, all people matter. Therefore, attitude counts. What you say is as important as how you say it. Give them the love sandwich (meaty truth sandwiched in between two pieces of affirmation). Give them every piece of information and available opportunity to become the type of person they need to be and show themselves teachable. Of course this assumes that we are being teachable ourselves. As such, we should remember that with every relationship there is something to be learned.