In graduate school, at the first meeting of an American poetry seminar that turned out to be wonderfully heavy on Emily Dickinson, the professor asked us to introduce ourselves by going around the table and disclosing our worst fears. As soon as she said it, the professor withdrew the prompt. “No, don’t say your worst fears, say your second worst fears. It’s too terrible, as an adult, to claim your worst fear. ” She paused. “What if it came true?”

My second worst fear is a wood chipper, those little green or orange monsters with big metal teeth that get lugged around by tree jockeys and that eat branches and trunks. Last fall, on my way to work, I saw one on Amory Street in Brookline and sticking out of it was not a mouthful of hemlock but the blue-jeaned legs and ass of a man. I was riveted and terrified. As I drove closer I could tell that he was intentionally face first inside the jaw, fixing it, I gathered. A couple of other tree guys stood around, unperturbed and waiting.

A healthy respect for the destructive power of machines may be rational (as may be the fear of waxing, which was the pick of another female grad student in my class). However, sometimes a fear grows until its size in one’s imagination becomes irrational.

A friend of mine, an artist, has an ex who has diabetes, as I do. Things are not going well for him, and I encouraged her to encourage him to make his way to the Joslin Diabetes Center, where he would get help with his medications, diet, exercise routine, and even his feelings of discouragement. “They will take care of all of him,” I assured her. The thought of this buoyed her. Recently she wrote to me: “Would you be willing to talk to him? He wants to go and he seems reluctant to go.” Ah, of course.

For years I have wanted to try yoga, I told this artist friend. Although I deeply, deeply wanted to do this, I was reluctant or scared for some reason. I do not know why. Finally last Wednesday I went. I had to push myself — quiet the chatter in my mind that was making up excuses — to go. Within the first moment of meeting the teacher, I loved it and continued to as the hour unfolded with time seeming not to pass. Now, having done the first hard thing (starting), I feel so relieved and happy at once.

Reluctance and fear are fraternal twins, and that is interesting. There are other members of that emotional family: desire and avoidance, for example, and distant cousins anger and sadness. One pushes; the other wants to obstruct.

When I bought my custom ice skates, the first step on my secret plan to becoming a good figure skater by my 50th birthday (and “good” will be defined by me), I walked around the store in them for a long time, trying to think my awareness into my feet. How did they feel? Was I secure, but not comfortable? (“Get that word ‘comfortable’ out of your vocabulary,” said Glenn, the owner. “I don’t want you to be in pain, but I don’t want you to be comfortable, either.” He said the word the way my father would: “cummft-uh-bul.”) Glenn said it was taking me a while and wondered if I should try on another pair. “No, I’m just trying to be thoughtful.” He smiled devilishly, that old skater. “We call that cautious.”

Why does caution get such a bad rap? Doesn’t caution have an evolutionary function? Some people had to be willing to rush out to chase and kill the wild boars, but didn’t some people have to figure out strategy, ways to preserve lives when risk is undertaken?

Caution and thinking are also related. I heard a famous scientist recently tell a room full of undergraduates: “Avoid the seduction of over thinking. We could sit around and plan our experiments forever. The thing is to just try something.” Having been accused of over thinking before, I thought, He’s right, and also wondered, When does thinking become too much thinking?

Last week at GLAD I talked at length to a caller who is experiencing discrimination on the job because of his sexual orientation. We walked through the steps he could take in filing a claim or consulting an attorney, both of which he was gearing up to do. He wanted to talk, too, about the uniqueness of his situation: in his workplace, he is the first openly gay person among about 300 employees. He had a feeling that this personal episode of discrimination was going to lead to some political and public activism, and he wasn’t sure he was up to it. “I’m 42 years old,” he told me. “Not some young turk. I don’t know if I have this in me.” I heard at once both the retreat and resolve in his voice; he was backing up in preparation for going forward, I sensed.

There is something about age and experience that makes us resistant, cautious, fearful. For some of us, it may be in our natures anyway: We stop and think before we act. (Yup, that’s me.) I suppose sometimes the stopping and thinking can go on too long, and the imagination can enumerate and elaborate too many dangers. We know too much.

My skating teacher, Mark, watched a bunch of adult novices make our first attempts at a basic spin. We skated into it; we hesitated at the crucial moment; we stopped. No one completed the loop he had traced with his blade on the ice. “You have to push through your fear.” He watched us try again, haltingly, and added, although we hadn’t asked, “Yes, you will fall.”

I found that to be one of the most comforting things a teacher or mentor has ever said to me. It made fear seem normal and necessary. And something to be skated, with resolve, into. I will fall, and it will hurt.

And the falling, hurting, and getting up once won’t banish fear. A person can feel fear and still act.