Excitement and fear are the same
When you feel one try to interchange it with the other.
I have a set of workshops coming up that make me nervous.
To interchange the nervousness with excitement I will take all the reasons to be excited about the workshop. From the things I will learn, to how I will feel after a successful workshop to interact with new people, these are all exciting when thought about positively. Taking these and associating them with the nervousness I feel makes me think of that nervousness as excitement.