Read the following dialog and answer the question.

Sandra and Chloe work at the same company, but recently Sandra is quite busy with her work. They decide to eat out on this lunch break to have a chit chat.

Sandra: I haven't told you what happened yet, have I?

Chloe: I haven't heard anything.

Sandra: Mr. Tjia, our HR manager, offered me a promotion, and I took it. I've been waiting for the past two years to get this chance, and it's happening now!

Chloe: Are you serious? 

Sandra: Yes, I am so excited about my new role. But you know, sometimes I still wonder if I can do my best or not. I am happy and anxious at the same time.

Chloe: I believe you were the best choice for that promotion. I really do. You've been working so hard, and you deserve it. Congrats dude!

Sandra: Appreciate that.

Chloe: You have no idea how happy I am for you.

Sandra: For real?

"I am happy and anxious at the same time."

The word "anxious" means the feeling of ....