There are a number of points at which leaders can grind to a halt:
1. When they are doing too much and unable to reorient their priorities
2. When they hit the unfortunate age point where the line on the graph of increasing responsibilities meets that of declining energy (incidentally this is a crucial re-evaluation point in all ministries. Fail to deal with what happens when the lines cross and all kinds of negative consequences arise)
3. When the level of resistance to change and growth in the church is greater than the resources that can be mustered to support it
4. When a leader knows that the personal emotional consequences of taking a particular action are likely to be unbearable. We never decide knowingly to take decisions that will force us over the edge
This last one varies according to a number of circumstances: the leader's own emotional state of well-being, how naturally they take to fresh initiaive, how good they are at inviting and leading others with them, etc. But maybe the biggest factor is whether they do it with others or on their own. The limit of what is emotionally possible is far higher with a (biblical, plural) team, working well together, softening the discouragements, sharing the joys, than it is for one person alone. Basically teams have more emotional capacity than a single person and therefore grind to a halt far less easily.
If you are leading on oyur own in a church, isn't it about time you asked yourself why?