Here are a couple of suggestions:
#1 Practice showing more energy in front of a mirror
This is feedback I implement before I am speaking and/or interviews. I have somewhat of a story and/or script of what I am practicing and I will do it in front of a mirror. What I do instead of just speaking, however, is literally scream the content. I try to go way over the top so that when I am in the real-life scenario and I naturally slow down (we all do this when with other people), I still have some of that increased energy from practice.
#2 Find things you really are interested in
This may seem like a no-brainer but most people I have met trying to break into a consulting firm have spent so much time trying to break into institutions, get good grades and try to mold themselves into others that they tend to be pretty shallow in their interests. So when they are interviewing they offer vague ideas ("I want to work with social impact companies", "I'm passionate about fixing health care."). These are great idea but everyone is on board with these already and you probably aren't as fired up as you'd like.
So how do you get the type of interests such that you naturally show that energy/drive AND make the interviewer want to learn from you? This is hard, but some suggestions:
- Think about the last time you lost track of time. What were you doing? Why does it matter to you?
- What is something people come to you for that you actually like doing?
- What is something that you've told people you're interested in but haven't actually pursued.
Now take an inventory of some of those things and start seeing how you might be able to share some of these during your interview and how it might relate to the work the firm is doing. For consulting, the firms do such a wide variety of work that you should be able to find something. In terms of the things you haven't pursued, challenge yourself to read an actual book about the subject (hint: ask 3-4 people in that field "what is the book everyone should read but doesn't).
These are a couple ideas - I hope they help!