How to overcome my resistance to lecturing? I am in a situation where I have several adult students for an all-day career training program that runs for about a year. So, they and I sit in the classroom most of a normal work-week. I decide when to get up and lecture. Although I tell them to raise questions any time, they rarely do unless I ask.

I enjoy speaking in front of the class, but because it is not on a particular schedule, I usually find that I have trouble motivating myself to get started. I don't have employee reviews or a mentor. My feeling in class is similar to how I have never gotten used to making phone calls: every time, it is like jumping into cold water, it never gets any easier. (I would rather talk in person. I am almost 50, by the way, and male.) How do I get beyond this basic motivation hurdle?
I don't enjoy lecturing either and yet my student reviews ask for more lectures even if I prefer discussion. What I've done for some classes is prepare a portfolio of 15 minute mini-lectures that are on one specific point, targeted, succint, and within the attention span (maybe) of 18 year olds.

You might also want to create a similar grab bag of canned material so that when a particular topic arises, you can easily lecture on it. 

Otherwise, the only other way is to practice. I've realized my own aversion to lecturing is something I need to work more on, so I deliberately designed a large lecture course that was 100% lecturing, rather than the smaller seminar courses that I prefer.